The latter part of Season 1 sees more or less every other main character trying to encourage Fitz to first acknowledge his feelings for Simmons and then admit them to her. But every time he tries, she thinks he's talking about something else, and, when she confronts him with a question about his hostility towards her other potential Love Interest, he dries up completely until he manages to come up with another semi-plausible excuse. Even when they're both expecting to die, he still can't bring himself to tell her, but asks her to "let me show you" via an attempt at a Heroic Sacrifice so she can live.
Late in Season 5, after May tells Coulson that she loves him, Coulson repeatedly tries to reply and fails each time. One gets the feeling Coulson understands Fitz a lot better now.
Big Wolf on Campus has Tommy trying many times to make his obvious crush on Stacy known to her. While it's pretty apparent that she suspects this and likes him in return, kisses, dates, hugs, or other intimate moments are usually interrupted by Tommy turning wolfy (caused by feelings of extreme emotion) and thus forcing him to run away.
Subverted in "Once More, With Feeling", in which several "Can't Spit It Out" plot threads that could have been milked for weeks, if not seasons, are dragged into the open by a demon's musical curse.
In Season 3's "Revelations", Willow wants to admit something to Buffy—which gets interrupted by a fight. Then Willow lies to Buffy to avoid saying what's going on and it later nearly costs Willow her relationship with Oz. Could've saved a half a season's worth of relationship drama (and she helped break up Xander/Cordelia).
Yet another example was Xander's crush on Buffy in the first season. It took the entire season before Buffy caught on to the blatant hints as well as Willow's crush on Xander.
A different application of this trope occurs with the Spike/Buffy relationship in Season 6, which she conceals from the Scoobies because she's ashamed of it. Tara eventually finds out, but has to guess it from Buffy's expression. It's only when she says to her old flame Riley, "I'm sleeping with Spike," (even though he already knows, having caught them in bed together) that Buffy finds the courage to end their Destructive Romance. When the Scoobies find out after the event, they're shocked, but generally supportive as they know Buffy has been going through a rough time.
Buffy herself admits she has a hard time saying "I love you" to anyone, likely due to how Angel's Superpowered Evil Side crushed her completely when she told him. The only other times she says it are to Dawn and to Spike right before he pulls his Heroic Sacrifice.
The Cheers episode "How Do I Love Thee? Let Me Call You Back" has Sam unable to say "I love you" to Diane. At first she's upset, but at the end of the episode, she decides that Sam is so used to saying it to women and not meaning it, that the fact he can't say it to her means something.
The titular character averts this pretty hard, since he seemingly can't stop telling Sarah about how he feels about her, even though their relationship is supposed to just be a cover. Sarah, on the other hand, plays it very straight for the first two-and-a-half seasons.
Sarah seemingly rubs off on Chuck in early season 3. Because it seems like they could save themselves about a dozen episodes' worth of heartbreak if they just got together and had one honest talk. Instead, they seem to be airing out their problems to just about anybody but each other. And because Chuck has to hide his secret from his family and friends, he can't even give them the full disclosure.
A fairly dark example from Coronation Street. The police arrive at Gail's house and she is annoyed at them for being there. They have a hard time breaking some news to her and she tells them to go ahead and "spit it out" so they can leave. It turns out they found her husband's body floating in a river.
See also The "I Love You" Stigma, as the series does not allow the Doctor to utter the words "I love you" to anyone on screen, leading to scenarios such as...
"School Reunion": The Doctor tells Rose that he leaves his companions behind because he will always outlive them:
The Doctor: Imagine watching that happen to someone that you... Rose: What, Doctor?
In "Doomsday", after Rose chokes out "I love you" to the Doctor (transmitted as a short-term hologram into the parallel world she's trapped in), it's his turn. "Since it's my last chance to say it... Rose Tyler—" And then the transmission cuts and he vanishes.
Even when he gets a second chance to tell her in "Journey's End", the Doctor is too broken to say more than "Does it really need saying?". However, his part-human clone fares better.
Also in "The Satan Pit", where it looks like he might finally ask another character to pass "I love you" along to Rose, the Doctor bails out at the last minute — in a very sweet way, mind. "Tell Rose– tell her... Oh, she knows."
"Last of the Time Lords" subverts it, as although Martha doesn't say the words when she admits that she was in love with him, it's clear that the normally-Oblivious to Love Doctor knows exactly what she's on about.
"The Lodger": Everyone, including the Eleventh Doctor, can tell that Craig and Sophie are interested in each other. But neither of them say anything until the events of the episode.
"Let's Kill Hitler" reveals that this was a problem for Rory before we met him. In this case, Cannot Spit It Out + Single-Target Sexuality = the girl he's in love with assuming he's gay. When Mels tries to get them together, he panics and runs out of the room before Amy catches on.
In "Face the Raven", the Doctor appears to be on the verge of telling Clara about his feelings for her as she prepares to meet her death, but she cuts him off with a tender hug instead, telling him she knows what he's about to say.
Especially during the Twelfth Doctor era, the writers have had the Doctor use euphemistic statements instead of straight "I love you", with three major examples occurring in "Dark Water" (confirmed by the showrunner as meaning "I love you"), "The Girl Who Died" and "Hell Bent". Clara herself has done this with regards to the Doctor on a few occasions, using alternate wording rather than a straight ILY.
In "Eve of the Daleks", Dan Lewis finally gets Yasmin Khan to admit the unrequited crush she's had on the Thirteenth Doctor for years. Dan encourages Yaz to confess her feelings to the Doctor, but Yaz responds that she's never told anyone, not even herself. Dan later tries to bring up the subject with the Doctor, who (as usual) pretends not to know what he's talking about, even though it's implied the Doctor shares those feelings.
The first season of Everwood. One of the fundamental sources of Ephram's antagonism toward Andy is the latter's seemingly-inexplicable decision to uproot his family and move from New York to the eponymous little mountain town. We learn in Episode 1 that Andy did it because his wife made him promise before she died. Ephram even points this out in the season finale after Andy finally tells him (after they've worked out their differences): "You know, this would have been a lot easier if you had told me straight away."
Firefly has an example with Simon and Kaylee. Simon is rather distracted with protecting his sister, while Kaylee is concerned by the class divide. It is the source of much UST until the end of the Movie.
Niles spends seven years pining after Daphne, his father's physical therapist and (default) housekeeper (in fairness, he does spend much of that time married). Despite trying to confess his feelings to her several times, his attempts are continually thwarted (usually owing to his own fear of rejection or, unwittingly, by Daphne herself). He remains unable to give voice to his emotions until the eve of Daphne's marriage to another man, and even then only after learning that Frasier has already let slip Niles's little "secret".
In the final season of the series Frasier and Niles's father, Martin, displays a similar inability to confess his growing feelings for his girlfriend, Ronee.
After they finally sleep together Bulldog genuinely develops feelings for Roz but can't bring himself to admit it. He starts scaring off the men she tries to date so she'll spend more time with him instead. After Roz catches him threatening her latest date she angrily confronts him, assuming that his looking after her daughter and making her dinner were just him attempting to seduce her (which he's done before in the past). Bulldog finally admits that he's genuinely in love with her...but Roz doesn't feel the same way.
Non-romantic version between Martin and his sons. Ever since they were children there was an intellectual gap between the three, and Martin's always been incapable of saying "I love you" to them, a fact that caused some disagreements between him and their mother, and is something he's concerned about. As adults, Niles and Frasier point out he's said he loves his buddy Duke, though Martin insists he said "I love ya", which they'd still take. Eventually, he does manage it.
Ross doesn't tell Rachel he loves her for the entire first season, chickening out every time the opportunity arises. This has the unfortunate result of Rachel only finding out from Chandler while Ross is on a trip to China, and when she realizes she loves him too, he's already met someone else there. Rachel herself then falls victim to this. She spends a good few season 2 episodes being unable to confront Ross about her feelings. It takes a lot of wine and borrowing a stranger's cellphone to spit it out properly.
Subverted when Joey developed feelings for Rachel. His hesitance was more due to her being pregnant with Ross's baby (though they were no longer together) and he eventually did work up the courage to tell her.
Inverted with Chandler's feelings for Monica—he Can't Hold It In. They are actually together, but are very cautious in moving forward, and vaguely describe their relationship as "being on London time", "goofing around", and "two friends who just want to spend more time together". At one point, he blurts out that he loves her and freaks out.
Meanwhile, Monica knows she loves Chandler but decisively holds off saying so until he'sready. A justified case of this trope.
A non-romantic version occurs in "TOW Where Monica and Richard Are Just Friends". Phoebe's new boyfriend likes to wear shorts while working out and doesn't realise that he keeps accidentally exposing himself in them. The guys notice right away but they barely know him and don't want to bring it up. When Phoebe finds out she doesn't want to say anything because their relationship isn't that close yet. Eventually Gunther steps in and asks the guy to cover himself up while in Central Perk.
Game of Thrones: Sam, either because of his oath or his overall awkwardness, is unwilling to admit any romantic feeling for Gilly despite her less-than-subtle hints that his affection would be welcome.
Almost every single thing that happens between Serena and Dan towards the end of the first season of Gossip Girl could have been avoided if she had just told him about Georgina.
On Happy Days, Fonzie cannot bring himself to say "sorry" when he's done something wrong to someone.
The second season could have been about fifteen minutes long if characters who were on reasonably cordial terms at the end of the first season a) remembered each other's phone numbers and b) bothered to discuss the, y'know, impending pestilent apocalypse with each other.
The Mohinder/Bennet subplot was a particularly awful in this regard: Mohinder spends the entire season obsessing about the world-killing virus. Bennet waits until the second to last episode of the season, after their partnership has imploded and Mohinder has consequently shot him, to mention, "Oh yeah, the Company has been experimenting with that for decades."
Season One has a number of more specific examples of this, with metahumans hiding their powers from others. Particularly notable are Nathan's constant lying to everyone about his flying (he doesn't even think to tell his invulnerabledaughter what he can do), and the half-dozen or so times Claire tries to tell her parents (or, as she later admits, "trying to not tell" them) about her healing.
Barney goes the entire fourth season without telling Robin he's in love with her, mainly because he's terrified she'll laugh him off because he's built such an infamous reputation as a shallow, womanizing sleazeball. He does tell Lily (who then tells Marshall) and Ted figures it out halfway through the season, but Lily and Marshall don't know Ted knows and vice versa, so all three of them sit on their hands in impatient silence for several months waiting for Barney to get a grip or Robin to get a clue.
This also comes up in Seasons 7 and 8, again with Barney and Robin while they deny their feelings to themselves/everyone else, until they got together again.
Back in Season 2 when Ted and Robin were dating, Robin tries to summon the courage to say "I love you" to Ted. She almost does, but at the last second, rather than uttering the three dreaded words, she blurts out "falafel".
The last two episodes of the first season of Jeeves and Wooster has Bertie making several attempts to get Gussie to confess his love for Madeline Bassett. The first time, Gussie loses it just a little and starts rambling on about newts at length until Madeline, who is actually waiting for him to confess his love, gets fed up and leaves.
On Lizzie McGuire, Gordo pines after Lizzie for the entire duration of the show. He nearly tells her several times, but falls victim to this trope. Lizzie ends up finding out from Kate, not Gordo. The Movie finally gets them together.
The episode where they all think Sawyer has Shannon's inhaler. If he just told everyone he didn't have it, there would have been no torture, but also no first Kate/Sawyer kiss...
And then of course, the castaways ignore good advice that is spit out. Even by themselves. "Don't wander alone in the woods full of tree-smashing monster-thingies." Always good advice. But no...
There is no character on Lost who is capable of completely summing up any event completely. They'll tell one mysterious event on an expedition, but will not tell the rest. They also never pull everyone at the crash site together to compare notes.
This drives most of the entire story of Mad Men. If Don Draper came clean about his "dark secret", then he would be able to straighten things out with his wife, stop looking over his shoulder generally, and would have saved his brother's life. Near the end of season three, he does come clean to Betty about it, but only after she forces his hand by finding out about much of it herself. At the end of the season, it looks like they're headed straight for a divorce.
Married... with Children: It's Valentine's Day, and all Peggy wants is for Al to say "I love you". He'd rather have sex.
In Merlin, most of the problems presented in each episode could be quite easily solved by briefing King Arthur as to what is going on. Somewhat justified because Merlin's magical abilities have to be kept secret, and displaying his knowledge in certain situations could lead to suspicion being cast his way. Also, on the occasions when he does try to warn people about some imminent danger, they generally refuse to believe him — even though he has been proven right again and again.
Doubled down in "Tableau Vivant", a third-season episode of Modern Family. Phil can't bring himself to tell Mitchell, his brother-in-law, that he's fired as the new agency's lawyer. Mitchell can't bear to tell Phil that he really doesn't like the work, which is in addition to his regular job.
One of the worst ongoing examples is from Monk; the title character has obsessive-compulsive disorder, but it's almost never mentioned, even when it would help. On one occasion, he shook hands with two white women, then a black guy, then asked his assistant for a wipe, like he frequently does. The black guy assumes Monk is racist, and explicitly asks him if he has any excuse. They tried to say Monk wasn't racist with Natalie saying "He loves Rainbows!" and Monk doing a rainbow-type of a hand motion.
The Office does this with Jim and Pam, with Jim not revealing his feelings for Pam. In one episode, Jim has been jinxed into not speaking and Pam tries goading him into talking (and thus, losing the game): "It looks like you have something to say." Cue longing look that says more than words could. He eventually spits it out in the season two finale.
In Once Upon a Time, a number of times characters try to make confessions to others but are unable to finish.
David's unsuccessful attempt to confess to Kathryn that he and Mary Margaret were having an affair.
Emma tries to take back her lie to Henry about how his father died, but can't bring herself to do it.
In one episode of Psych, Henry is given fifteen seconds to deliver a final message to Shawn in the hypothetical situation of dying in a plane crash (like the victim of the episode). He stumbles over his words until the fifteen seconds are up. Only after Shawn stalks out does he string together "I love you."
A lot of problems in the show Reaper come from Sam's inability to tell Andi about his problem with the devil.
Seinfeld has the standard episode about The "I Love You" Stigma in Season 6, but later inverts it with Season 7's storyline about George's engagement to Susan, which instead boils down to his inability to go through with the breakup conversation. Since his various backwards Please Dump Me measures have no effect, the problem turns out to literally only be resolvable by Susan's sudden death.
George: ...I can't face that scene. You know what kind of scene that would be? I'd rather be unhappy for the rest of my life than go through something like that. I CAN'T, I CAN'T. I tried to psyche myself up a million times, I cannot go through that.
Inverted when Lisa Landry met Terrence in Sister, Sister. Lisa did spit it out to Terrence when meeting him. Unfortunately for both her and Terrence, it was the wrong kind of "spit it out."
Smallville: Many problems befalling the characters stems from Clark's refusal to tell anybody about his powers (though Clark's fear is quite justified considering that superpowered individuals and their loved ones tend to get targeted by government conspiracies and mad scientists in the SV-verse).
The Spencer Sisters: The first season finale has Alistar backing out at the last minute on admitting to Victoria that he has feelings for her.
Odo spent the better part of a decade in love with Kira without ever being able to confess his feelings to her (well, unless you count his Anguished Declaration of Love to what turns out to be a changeling that has taken Kira's form in "Heart of Stone" or the confession made by a 200-year-older future Odo in "Children of Time"), to the point that when he finally does Jadzia comments "It was about time".
The subplot of the Season 5 episode "Dr. Bashir, I Presume" involves Rom attempting to confess his love for Leeta, only to repeatedly chicken out. For her part, she feels the same way, but mistakes Rom's timidity for lack of interest. In the final scene, as Leeta's about to leave DS9 with Zimmerman, Rom finally tells her how he feels. Much to Zimmerman's disappointment, she returns Rom's affections and decides to stay.
Star Trek: Voyager. In "Gravity", Tuvok is stranded on a planet with an alien woman who falls in love with him. However, Tuvok is Happily Married and as a Vulcan has been raised to believe that Love Makes You Crazy, so he refuses to admit to any affection on his part. Fortunately Vulcans have the ability to mind-meld, which he does at the end of the episode to share his true feelings.
Mike gets pretty easily flustered telling Eleven how he feels about her, to the point that Mike cannot even say the word "love" around Eleven. In the first season finale, Mike is explaining to Eleven how she'll be a member of his family, with his older sister Nancy as one to her, but he doesn't want to be like a brother to her, so to explain, he instead kisses her. Eleven's face lights up in absolute delight afterward. In Season 3 after getting back together following a temporary break up, Mike gets into an argument with Max and Nancy about El overtaxing her powers to find the Mind Flayer, and in a rush of emotion finally admits that he loves her. However, since El had been in the other room at the time, she didn't hear him. At least, that was what Eleven let Mike believe; in the season finale Eleven reveals that not only did she hear Mike, she also loves him.
Jonathan, being an aloof introvert, is unable to spit out that he's got a crush on Nancy. Likewise, Nancy is unable to admit after season 1 that she's got feelings for him. They're so blatantly dodgy around the subject that Murray Bauman has to push them to act on their feelings.
Tian of A Tale of Thousand Stars tries to get Chief Phupha to admit his feelings, but the latter refuses to admit it, as he's afraid of hurting Tian and isn’t certain he’s the one just yet.
On Teen Wolf, Derek spends a sizable chunk of the first season being a creepy, cryptic lurker and leaving Scott believing that he is the one that turned him into a werewolf. He also could have been more forthcoming with details about what Allison's family does.
In Terminator: The Sarah Connor Chronicles, if Riley talked to John, John talked to Sarah, Derek talked to either of them, Sarah told people where she was going OR they just had a nice, normal family dinner once in a while, they would figure out in about 5 seconds that Jesse was holding Riley hostage, that she had pretended to be a school official to get info on John, was lying to Derek and is not on their side. Instead they remain oblivious and one of them gets killed.
In To Love And Die, Hildy tracks down her estranged father, stalks him to his workplace, gets a job working for him, finds out he is a contract killer, follows him to and interrupts his latest hit, is consequently captured by his associates and interrogated on suspicion of being a rival contractor. One would think that the perfect time to finally reveal that she's his daughter would be when he has her tied to a chair and is demanding, on pain of death, to know who she really is, but even then, she manages to spend the entire interrogation rambling, and doesn't blurt out the truth until he's already given the order to kill her and is seconds away from leaving the room (fortunately, he listens).
Ray finds it very difficult to tell her mom that she's seeing both Kieran and Gemma, never exactly managing. Her mom realizes it anyway.
Gemma also never manages to tell her dad. He in turn never manages to tell her that he's dying of cancer.
The Untamed: Jin Zixuan with Jiang Yanli. It takes him several tries until he finally manages to tell her that he likes her. And he didn't exactly help matters by saying he doesn't want to marry her and getting into a fight with her brothers over it, only to change his mind later when he falls in love with her.
Velvet: Ninety percent of Pedro's problems in the first two seasons would have been resolved if he could have just told Rita he loved her without five minutes of nervous babbling.
Wednesday: It is revealed that it is hard for Wednesday to admit that she and Enid are friends due her closed off nature. After their fight, it quickly becomes clear that Wednesday wants Enid to move back into their shared room, but she simply can't admit it or ask Enid to come. Even Thornhill points out that it is clear Wednesday misses Enid and wonders why it is so hard for Wednesday to admit it.
In Zoey 101, Chase spends 3 seasons pining after Zoey. In one episode, he tries to text his feelings to her, and her cell phone falls into a fountain. After Zoey finally finds out how he feels...he gets Put on a Bus to England.
