"This is the purpose of living for those who have no life". The fact that ADA says it with the same calm finality with which she says everything else, adding only a small pause, makes it so resigned and sad.
The entire shown character of Viola in Idolo. She gets diagnosed with a VERY dangerous dosage of space radiation quite early on when she was just a child, making her condition as a Martian even more precarious than most are, lost the rest of her family by the time she was older, but that didn't stop her from joining BAHRAM to take the fight against the corrupt sect of the UNSF who mistreat the Martians every chance they get, even though they're just adding more fuel to BAHRAM's fire to fight them. She falls deeply in love with Radam, but unfortunately he ends up already having a girlfriend by the name of Dolores. Needless to say, by the end of it, if you aren't crying heavily, then you simply are inhuman. Another is shown beautifully in the Delores season finale episode where Rebecca (shown mentally as Viola herself), shows up at Radam and fake-Delores' wedding in his mental realm, and is then brutally shot in the heart as she attempts to get closer to him, as if her ungodly trauma/sadness wasn't bad enough, she gets shot by her own Beloved...
Dolores: AI. Artificial intelligence, but in Japanese, it means "Love"...
The first game has a bad ending that's really hard to achieve by normal means unless you go out of your way to do so but definitely qualifies as a Tear Jerker nonetheless. Fail all the SOS missions, and Thunderheart will be brutally and abruptly killed by an explosion as he's talking to Leo. ADA will confirm that what caused the explosion was Jehuty destroying the colony shaft; in doing so, it hit one of the colony's underground lifelines. Cut to a grim The End screen, with a destroyed city in the background, and the game returning to the title screen. ADA's Brutal Honesty and Leo's reaction set the deal, as ADA doesn't just sound like she's berating Leo; she also sounds like she's berating you, the player, for screwing up this badly, if not outright going out of your way to cause this.
ADA: In other words, you killed him.
Leo: But, I didn't mean... *cut to The End screen*
The aftermath of the final fight against Viola in the first game: Leo manages to win, but one of the mines set up by Viola explodes right next to her Orbital Frame, launching it outside the station, only for it be caught and dragged by Jupiter's gravitational pull. Leo asks ADA for a way to rescue Viola, but Viola herself interrupts him over the radio channel...and what follows is an absolutely heartbreaking sequence set to a haunting piano piece, in which Viola slowly breaks down as she burns up in re-entry, starting by chastising Leo for his naiveness and selfless nature in trying to save her...as she makes it clear that if he does, she will kill him and everyone he loves, and will continue killing after that. As she is slowly dragged to a horrible death, Viola opens up and rages about how incomprehensible it is that Leo triumphed over her, as she acknowledges just how opposite their very natures are, and how she was slowly turned by war into the monster she is, all while she lost the man she loved, her teammates and even her own nature as a woman to conflict, always surviving because of her talent and strength, the only things she had left as a human being, only to, after all this time, her defeat so she can fall on the battlefield. As a final wish, she asks Leo if she was strong, to which he replies he still finds it hard to believe he is still alive after their battle, to which Viola, for the first time in the whole game, chuckles and thanks him for. And to finally hammer the point of Viola being just another victim of conflict and war, she suddenly remembers Radam and his love of the stars, just as her orbital frame disintegrates and she dies, finally at peace with herself, making her defeat and death absolutely heartbreaking, all by humanizing what had been an absolutely monstrous villain through the whole game in just one single, astonishing sequence.