Bliss Stage is the Trope Namer. If your Trust in any relationship is ever reduced to zero, that relationship "breaks". A broken relationship earns you a ton of Bliss points, more if you have higher Intimacy. Getting more than 108 Bliss is very bad.
Pandora's Tower. If you neglect Elena in spite of being reminded several times that The Power of Love is one of the few things that keep her curse at bay, she will die (by your hand, no less) and net you a Game Over before unlocking the last two towers.
A slightly better relationship with her will lead to another Downer Ending, with her turning into a mindless war machine, and Aeron joining her and the Towers' monster army.
In Persona 3, neglecting to pay attention to certain Social Links may lead to them becoming Reversed, which means you'll have to repair the Link before it can be leveled up again. (You usually have a month after they request some attention to return it.) Screw up once a link is reversed and it will Break completely, leaving you unable to summon Personas of the relevant Arcana. This is particularly an issue with romantic Social Links: date more than one girl at the same time - the amount of time you have to hang out with a girl before the link reverses is cut by a quarter each time you see a different girl. There are five such links in Persona 3 that will seem mutually exclusive if you don't have extensive knowledge of this mechanic. Good luck!
Persona 4mostly removes this mechanic, so two-timing is no longer an issue — especially with the fact the player doesn't have to accept a romantic attachment from the eligible girls to complete the link, unlike in the previous game. However, it's still possible to break Moon and Fortune by making particularly bad decisions along the way. The Updated Re-release of Persona 3 uses 4's mechanic, but it's possible to break the female protagonist's Star link by being especially insensitive. The game does tell you to carefully consider your answer.
Along similar lines, being enough of a jerk to your team members in Mass Effect 1 can alienate them to the point that Kaidan and Ashley will find excuses not to talk to you, and Tali will outright inform you that she's only sticking around for the mission and doesn't want to speak to you. (Wrex, on the other hand, seems to like you a little better if you're a jerk to him.) He probably sees it as Shepard having more of a backbone, being that Wrex comes from a society of Blood Knights.
Mass Effect 2 takes things further. The only way to make it through the Suicide Mission against the Collectors with everyone in your crew alive is for everyone to be loyal to you through doing their loyalty missions after recruiting them. And even then, this only gives you a fighting chance — making the wrong choices during the final mission and/or not upgrading your ship could very easily lead to you losing squadmates no matter how loyal they are. Even if you have her loyalty, Samara still tells Renegade Shepard that she's going to kill him/her after the mission is over. You can avoid this by killing her first. (Also, she doesn't actually kill you in the game. In addition, there are character-based conflicts where Shepard will have to take one side or the other (Miranda vs Jack and Tali vs Legion) if your Karma Meter is not high enough in either direction to overrule their argument on personality alone, meaning the other's loyalty will be lost.
Plays out on a larger scale in Mass Effect 3, with Shepard being dispatched to gather allies to help Earth against the Reapers, your actions throughout the game (as well as your performance in the multiplayer, and in the two tie-in mobile games) add War Assets to your side, or even lose them, to varying degrees. Some assets are mutually exclusive (that is, you have to favor one faction over another). Finish the game with insufficient War Assets, and you'll get the Bad Ending.
This is basically the entirety of Fašade. If Trip gets very upset with you, he'll kick you out, leading to a Game Over.
In Vanguard Bandits, on the main story path, you get the Bad Ending if the average Morale of your units is under a certain number.
Sort of played in The Elder Scrolls, where if your speechcraft skills fail multiple times, you'll make an NPC hate you, which means you'd better not drop a plot-important NPC's trust level to zero. Especially since some NPCs attack you when that happens.
In The Elder Scrolls II: Daggerfall your reputation with your various guilds can decline if you stay away from them for a while and, though you can never lose guild ranks, you can be ejected from the guild until your reputation with them zeros out.
This is a significant aspect of Sacrifice. At the beginning, you are able to perform missions for any deity whenever you choose. As you accomplish these tasks and the plot progresses, you gradually fall out of favor with those you ignore, until the endgame leaves you permanently aligned with one of them and opposed to the four others.
In Tsukihime, if you take a very specific path, you'll ignore all main girls to such an extent that you'll get a Non-Standard Game Over, and in the hint corner afterwards, you'll get told to "give the girls more attention".
Additionally, game over can occur at several points in Tsukihime if character affection isn't high enough.
In Katawa Shoujo, if you don't make enough of an impression on one of the five girls by the end of the first week, you die. This also happens if you make a critical mistake and alienate a girl at one of four points.
Inverted in Full Metal Daemon Muramasa: Up to the middle of the game you have to take a path where no one among the heroines has higher points than the others, else you will have to kill her.
In general, many Dating Sims and Romance Games will punish you with a bad ending if you haven't built up a high enough relationship with any of your potential suitors by a certain point. Some of these games make this ending extremely brutal as if to accentuate just how royally you screwed up, like Fantasia: Requiem of the Abyss that ends with you being murdered in your bed if you fail to get on a guy's path by Chapter 3 and Hatoful Boyfriend that ends with the genocide of the entire human race if you fail to complete a romance with anybirdie.
At one point in Neverwinter Nights 2, if you don't have enough influence with Elanee, she will leave your party and wander away (assuming you don't kill her instead). At the end of the game, The Dragon will try to lure some of your companions away from you, and those you have low influence with will fight at his side against you.
Bishop turns against you whatever you do, although he will bow out of the following fight if your influence with him was high (by explaining to him that he'd just be a pawn in the King of Shadows eyes). Qara, Sand, Ammon Jerro, and Neeshka are all offered the opportunity to turn on you if you were a jerk to them. If you choose to side with the King Of Shadows a high influence will get Bishop to help you in the fight against your former teammates.
In Splinter Cell: Double Agent, Sam will lose if he reaches zero "trust" with either the JBA or the NSA. As the name suggests, you're playing a Double Agent, so losing the trust of the organisation you're infiltrating fails the mission, while losing the trust of your own agency gets you blacklisted as a rogue agent.
Maid RPG has this as one of the main features (that and the weirdness, of course). Although the GM can choose to simply assign you to a different mansion, you are getting removed from the campaign either way.
The Thing is entirely based on this. Everyone in the game is so paranoid that if they lose all trust in you they immediately assume you are the Thing and start shooting at you. To make matters worse, they won't cooperate if they don't trust you enough. You can partially fix this by giving them guns, running blood tests to prove your humanity, or killing a member of the group that is a Thing and allowing it to expose its horrid form.
A large part of the story in Wizardry: Tale of the Forsaken Land revolves around interparty trust, which is what determines your access to the combos that are far better than individual actions and absolutely required to get very far. They also influence the success rate of resurrections... which given how often people will die if you don't keep your trust up... Oh and if the res fails twice, that character is Forever Dead. Even if it works though, dying and coming back negatively affects stats, in particular HP (so that they're more likely to die again) and trust (so you have a much harder time breaking the cycle). Screwing up your trust can effectively force you to restart the entire game.
The mediocre GBA version of Spirit: Stallion of the Cimarron has you gaining the trust of wild horses and leading them through various areas. To keep their trust, you had to give them food and water. If trust got low enough, they'd refuse to let you ride, and would eventually run away from you. You can imagine how fun this was in the desert level.
Several games punish you for not befriending (or romancing) certain characters by taking them away forever. In Harvest Moon 64, you could lose one of your potential brides and a rival this way, and that also meant not completing your recipe book since they had recipes they'd take with them.
In A Wonderful Life, losing townspeople meant that you'd lose their "influence" over your child's interests. Either way, they'd be generally Lost Forever as NPCs. A Wonderful Life also requires you to be married to continue the story. So if you blow off all of your potential love interests at the beginning of the game or drive away your spouse later on, you get a game over.
Rune Factory Frontier inverts this trope in one case. Pursing one of the potential brides, the maid Tabatha, will at one point eventually cause her sister to arrive. Continuing to do so means that in completing the final task required to marry Tabatha her sister will leave.
In Grand Theft Auto (starting with GTA San Andreas), you can date certain girls; once they like you enough, each one provides a special service (e.g., getting your weapons back when you're arrested, removing Wanted Levels, etc.). GTA IV added platonic friends — who basically work the same way, except for the lack of sex at the end of the date. If you don't take each NPC out on a regular basis (or you do things they don't enjoy when you do take them out), they'll stop being your friend/girlfriend, and you lose their special ability.
If you don't maintain a good relationship with your monster in Monster Rancher 2, it will be more likely to misbehave (losing you fights and precious training time) or even run away.
The Tokimeki Memorial series punish you hard if you totally ignore all characters except your target love, as they will be all too willing to "bomb" you, i.e. spreading bad rumours about you, and if you don't take measures to defuse those bombs, they will explode, heavily damaging relationships with all the characters you know. It's very hard to recover from a gone-off bomb with regular characters, and an essential Game Over with Nintendo Hard characters such as Shiori Fujisaki or Kei Hazuki.
In Dragon Age: Origins, if you annoy your party members enough or make choices that they don't approve of then they will either leave your party or attack you. The only character who will never leave is Alistair, but that's only because the mission to destroy the Archdemon is more important to him than anything else. However, if you choose to spare Loghain (which offends Alistair) Alistair will leave forever.
Morrigan will never leave the party either since she needs a male Grey Warden to complete the Dark Ritual. She will leave the party if you don't allow her to go through with it.
The only character who will never leave your party is Dog.
If Zevran's approval is not high enough by the time the Crows come for him, he will leave you for them and fight alongside them against you. Similarly, if Sten is in your party and his approval is not high enough in Haven, he will challenge you for leadership of the group
Averted in Dragon Age II. Companions gain different bonuses if they have high friendship or rivalry values. It's entirely possible to romance rivals as well, and maxing out a companion's rivalry will earn their Undying Loyalty as effectively as friendship. Presumably this is because they either respect you despite your differences (Fenris, Sebastian), want to keep an eye on you (Aveline), enjoy messing with you (Varric), or want to prove you wrong about them (Anders, Merrill, Isabela).
Actually, you'll be at a disadvantage if anyone's friendship or rivalry isn't maxed by the final mission, as depending on who you side with, they'll bail on you. But in Isabela's case, having friendship or rivaly at a high level by the endgame of Act 2 is essential to getting the Supplier achievement/trophy, which is already a Guide Dang It clusterfuck to begin with. Not to mention her friendship/rivalry has to be high for her to be usable in Act 3 at all.
In Tactics Ogre: Let Us Cling Together, the Ogre Battle spin off, your troops have a loyalty meter that will change based on your decisions in battle and during story scenes. Though you can't lose by having troops with low loyalty, your troops will begin to leave you if they don't agree with you or aren't treated well. In a game where Anyone Can Die and the enemies you fight level up with the highest leveled member in your team to ensure you never get an easy fight, having the strong surviving warriors in your party leave you can be crippling. Combining this with the fact that you don't always know which actions will effect which characters, and the fact that your actions will always prompt a range of different reactions within your team, and that things as simple as not letting your units move during battle, or attacking an enemy unit of the same nationality of one of your characters can result in a drop in loyalty, AND the fact that loyalty is a relatively well hidden stat that can never be measured exactly makes this game Nintendo Hard.
Only relevant in missions, but in both Mercenaries games if you do enough to become an enemy of the faction you're doing a mission for, you automatically lose the mission. Enemy factions also won't give you missions, which is the only way to get information on bounties (although that doesn't make the game unwinnable)
Soldier of Fortune II: Continually jeopardize the soldiers' mission in Colombia, and they will execute you on the spot for treason.
If a Relationship Boosted check in Monsters And Other Childish Things fails, or if a monster drawing upon the power of a relationship is PWZNED in a fight, then the relationship is "Shocked" and suffers a penalty as a result. Failure to repair the relationship in time can permanently damage it.
In Fallout: New Vegas, some companions will leave you if your reputation with a faction drops too low or goes too high, if you do things they feel are wrong, or in Cass' case, if your karma drops too low. This generally happens if you associate with Caesar's Legion since all the human companions hate them though the non-human companions are ambivalent at best.
Averted in Alpha Protocol. Negative relationship values with certain characters nets Michael different bonuses than positive relationship values. This can also be used to manipulate characters into doing what you want them to do since the game encourages you to be a Manipulative Bastard.
Applied to a factional rather than a personal level, this trope can be found in just about any grand strategy game / political simulator that tries to model the Cold War from the perspective of one of the superpowers. If the other superpower distrusts you too much, the nukes fly, usually leading to The End of the World as We Know It.
In Septerra Core there are two pairs of party members - Led and Lobo and Corgan and Selina - that hate each other's guts and any of them may randomly attack the other one during a combat, if you travel with both of them. You need to go on two subquests to repair their relationships. It's possible to avoid the trouble by not travelling with both of either pair at the same time, but not getting subquests done will bite you back hard at the very end of the game, when the party splits in three teams - and people who hate each other will end up in the same one.
If you manage to reach the end of Romancing Walker without being nice enough to (and getting enough events of) the other members of your party, you'll get as far as the second-to-last room in the game... after which the game will scold you for not trying to court the women. The only two recourses are to load a slightly earlier game and grind out enough secret points to make an eighth member available (whose existence is a Guide Dang It in itself) OR to load a much earlier save file so that you can get relationship values high enough to have a partner going into the final battle.
In the SimCity series, you get fired if your approval rating goes too low, or if you are in debt for too long. The first game rubs it in your face by having you thrown out of office by a mob of angry citizens led by your own mother.
In Hakuōki and its prequel game Hakuouki Reimeiroku, failing to develop sufficient levels of affection with at least one of the various members of the Shinsengumi inevitably has dire consequences ranging from Survivor Guilt to your death to an outright Kill 'em All ending.
In Virtue's Last Reward, choosing to Betray a sympathetic character generally leads to disgusted reactions from the rest of the group, especially if this person is currently incapacitated and unable to vote. Which makes the one instance in which betraying the unconscious Alice is the correct decision a massive wham episode for the player. In all other situations, choosing to Ally with an unconscious character is the logical decision. But if you choose to Ally with her, she kills you.
The CSI NY videogame gives Mac or Stella a meter while questioning NPCs. If you ask too many irrelevant questions (ie asking about the wrong evidence), your confidence meter drops and if it empties, you have to start over. Your end-of-case score is also affected.
This is the normal Game Over condition for Xcom Enemy Unknown: Lose the support of too many countries and they shut you down, going to Plan B and attempting to make peace with the invaders. It ends as badly as you expect.
If you don't exteminate enough subhumans" in KZ Manager, public opinion will drop until you are revoked from your post of concentration camp commendant.
In Hamurabi, if more than 45% of the population starve on a year, the player is deposed and "declared 'National Fink'."