This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / The Tigger Movie
"Rabbit, I miss him..." Just the Puppy Eyes and tears...
Tigger's completely heartbroken expression when he finds out that his "family" is really his friends in disguise and thinks that they see his family as a joke.
Topped off with Tigger goes walking into the snowstorm to find his real family. We get shots of Tigger looking back at his home. You see the pain and heartbreak on his face before becoming determined to find his family. Then you see his friends looking at him, heartbroken for having hurt him when they were trying to help. All of this is animated without a word of dialogue. The line as he leaves as well-
Tigger: I'll find them, and I have the letter here to prove it. So...TTFE. Ta-ta...forever.
The fact that it's Tigger tops it off. Seeing a character everyone is so used to seeing active and excited and happy in every bounce he takes through the word actually go through grief and suffer doubt in both his own identity and his relationship with his closest friends can rip you to shreds.
When Roo comes to Pooh begging him in tears to help him find Tigger.
In general, just the idea of Tigger discovering the actual implications of being "the only one": He has no family.
The worst part was near the end, when, certain that his non-existent family is coming back for him, Tigger ventures deep into the woods during a snowstorm. The sheer heartbreak on his face and in his voice as he suddenly realizes no one's there is just...
Tigger: I thought you were always there for me...
And then it just kept piling on the angst. Tigger's friends go after him in said perilous snowstorm and beg for him to come home and out of danger. The way Tigger painfully shouts "NO" makes you feel every ounce of what both sides are experiencing in that scene.
Just after the above "NO" scene, an avalanche starts. Everyone runs for the nearest object, the tree Tigger believed to be his family tree. Tigger starts bouncing with all his might to get everyone else to safety, and as soon as he tosses up his last friend, Rabbit, he gets swept away by the avalanche. Roo then goes in to rescue him. A shock chord plays when Tigger gets attacked by the avalanche, cue lots of flinching and shocked gasps.
For that extra touch, listen carefully, who is the person giving the most shrill and horrified reaction to Tigger's supposed demise? Rabbit.
Rabbit: Are you crazy!? It's not safe out here!
Tigger: Exac-ti-cally! That's why you should all go home where it's safe! But I've got to wait here in my family tree. For my! Real!Family!
Roo's role in the story is even more heartbreaking, spending the entire movie trying to cheer up Tigger and get his idol to notice and love him like a 'big brother', though is either ignored in Tigger's obsession to find his family, or makes things worse. This hits even harder during the climax where he repeatedly attempts to just hug Tigger though is distracted or ignored each and every time, until about the final two minutes when Tigger finally accepts his friends as his real family and thus gives special notice to his "bestest little brother". Having been mostly a side character in previous Pooh features, an enormous Woobie role was a good way to start Roo's ascention as a Breakout Character, suitingly just like Tigger himself.
And then there's the end credits song, "Your Heart Will Lead You Home." In fact, the end credits period, still drawing replicating events of the story but in the style of E. H. Shepard, the original illustrator of the Winnie The Pooh novels. The same heartbreaking story with an added nostalgic tear for fans of the original A. A. Milne books.
For Tokyo Disneyland's 25th anniversary, where the theme was love and friendship, they made this the main theme music for their Jubilation parade that was created for the festivities.
Roo begging Tigger to not leave him is absolutely heartbreaking...
A meta-example. Paul Winchell, Tigger's original voice actor, was scheduled to voice Tigger in this film, but was ultimately turned down by Disney, who believed his voice was too worn to replicate the character anymore. Winchell passed away shortly after the film was released, denied a perfect swan song as one of his most iconic characters.