Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Tear Jerker: Thor
Thor trying and failing to lift Mjölnir halfway through the movie. He walks up, a big grin on his face, and grabs the hammer...but he can't pull it out. He tries for a few minutes before falling to his knees and screaming incoherently at the sky. It's hard to describe the exact look on his face — it's like a soldier coming home to his wife, looking forward to his favorite meal, and finding out she doesn't even remember him.
Not long after this, a downtrodden Thor is taken into custody without a fight by the S.H.I.E.L.D. agents, despite tearing through them minutes ago to reclaim Mjölnir.
The trefoil sign appears as if to say, "You are not worthy" in what appears to be a small, quiet voice, making it even worse.
Loki's cruel lie when he claims that Thor's mistakes and exile have caused Odin to die of grief, and now their mother blames Thor and never wants to see him again. Thor pretty much hits the Despair Event Horizon at this point.
And after that Thor asking him "Can I go home?" like a little kid.
The scene where Loki discovers that he's a Frost Giant and Laufey's son. And when he's screaming about how it's obvious that Odin never loved him as much as Thor, Odin falls into the Odinsleep. Loki, realizing what has happened that he caused, looks horrified and slowly reaches out to hold Odin's hand before calling the guards in panic.
From the Fridge Brilliance page, the first thing out of Loki's mouth when Odin walks in is 'Am I cursed?'. He's essentially figured out who he is and clearly wants desperately for it to be wrong, because he's a sorcerer, and if he's been cursed then he should be able to fix it, but even that's denied to him — he's clinging on till that moment, but when Odin confirms it, the audience can practically see him lose it.
Odin accuses Loki of twisting his words during this scene, but you really don't need to do a lot of twisting to see how this conversation pushed the guy over the edge. Odin flat out states that his plans to use Loki for political peace no longer matter; so by extension, Loki (mistakenly) believes he no longer matters. At this stage Loki really looks like he's going to burst into tears.
And you can hardly say is 'I am the monster parents tell their children about' line is unjustified, given that we've seen that Frost Giants were the monsters he was told about as a child. It's basically the equivalent of a human child finding out they're actually the bogey man.
Loki. Sure, he's crazy and genocidal, but the crap that leads up to his messed-up-ness is really unfair.
What does Loki really want out of all his shenanigans? Love. He wants affection from his people and family, which he feels he's been denied all his life.
Check out the scene right before Loki lets go of Gungnir. I'll give you a minute to find it on youtube. Got it? Then you'll have noticed that he's crying.
Just listen to Loki while he's (more or less) begging Odin to understand his intentions. He sounds so young, you can hear the hurt little boy asking for reassurance from his father.
It's pretty sad for Odin, too. His final words to Loki before Loki let go probably ring through his head constantly. If he had just said something more compassionate and understanding, perhaps Loki would have accepted him to some degree but instead, Odin's final words were all he needed to hear to sink into the abyss. Made only worse by what happens after, because he probably saw everything and knew that in some way, he was always going to have to bear some of that blame.
In a meta example, it's really sad that Loki spent all this time wallowing in the fact that he wasn't his father's favorite, so much so that he never even realized he was Thor's favorite. And if there's one thing that's pretty clear in the movie, it's that Thor genuinely loves his little brother.
Thor talking to Loki through the Destroyer, begging him to stop his assault on the humans on his account, sounding so forlorn and confused as to why Loki hates him.
Thor: Brother, for whatever I have done to wrong you, whatever I have done to lead you to do this, I am sorry.
It becomes even sadder upon watching the deleted scenes because the music playing during Thor's confrontation with the Destroyer is a Dark Reprise of the music playing during a deleted scene from the beginning of Thor when Thor and Loki shared a brotherly moment.
Heck, on top of that, Thor tells Loki to kill him instead of continuing to attack his friends. The vain, greedy, cruel boy from the beginning of the film is willing to literally give up everything to save other people, and he doesn't want a fight when, in the beginning, he was eager to march into battle.
On the other hand, Thor doesn't realize how he and his friends had hurt Loki through the years.
The last line in the film: "She searches for you."
A blink-and-you'll-miss-it moment: just after Odin banishes Thor, Loki turns to look at him with a mixture of disbelief, hurt, and anger. If you wanted proof that that wasn't part of his plan, there you have it.
Crosses over with Heartwarming, but Loki's panicked calling for help when Odin slips into a coma. Regardless of how upset Loki was at that moment, he never wanted nor expected his father to be struck down.
In the deleted scene from before the coronation, we see Thor and Loki having a brotherly moment. If you see it before seeing the rest of the movie, it will just be heartwarming, but seeing it after you've seen the movie, after you see what Thor and Loki become, it becomes heartbreaking in hindsight because you just can't help but remember that before all of this happen, they were brothers.
Thor trying to reason with Loki before the climax. It's upsetting because of how relatable it is; most of us, if not all of us have been in that situation where a friend or a family member has for whatever reason gone off the rails and any attempt at reasoning with them is to no avail.
You'll notice while Loki is fighting, Loki is going all out but Thor is obviously holding back. Loki just assumes Thor is toying with him...Thor just doesn't want to hurt his little brother.