This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Spider-Man 2
"I'm Spider-Man... no more."
Earlier, Peter wakes Aunt May up from a nap, and before she raises her head and realizes what's going on, she asks Ben what he wants.
When Peter's glasses start to blur his vision again, considering what was motivating his powers to come back.
Peter daydreaming that he's talking to Uncle Ben, trapped in the memory of their conversation just before they go their separate ways prior to the wrestling match in the first film. When Peter tells Ben that he's retiring as Spider-Man, Ben looks so defeated and heartbroken. You can tell he's not only crushed that he feels he's died for nothing, but he's sad for his surrogate son, too.
Robbie Robertson's reaction upon realizing that Spider-Man has quit. While Jameson laughs triumphantly over Spider-Man's retirement, Robbie silently stands there with a look of pure heartbreak on his face as he gently holds Spider-Man's discarded mask in his hands.
May and Peter visiting Ben's grave on the second anniversary of his death, with May saying, "It wasn't fair for him to go like that. And it was all my doing."
When Peter returns home with May after visiting Ben's grave, he finally decides to confess to May his involvement in Ben's death, and how he was with Ben in his final moments.
Peter: Uncle Ben was killed that night...for being the only one who did the right thing. I...I held his hand when he died. I've tried to tell you so many times...
Right after his confession, May pulls her hand away from Peter and looks at him with a mixture of shock, anger, and heartbreak. She then silently gets up and walks upstairs to her room, leaving Peter to wonder if she'll ever be able to forgive him.
Peter David's novelization makes it worse. Peter tries to follow May, but May yells at him to "GO!"
Peter with no powers has a bit of a triumphant moment when he saves a child from a burning building. But then he hears from one of the firefighters that one person was trapped on the fourth floor and never made it out. This causes him to once again go through a big case of Heroic B.S.O.D. and wonder if he really had made the wrong choice in quitting.
Peter: Am I not supposed to have what I want? What I need? What am I supposed to do?
Jameson:It's All My Fault. I drove Spider-Man away. [...] Spider-Man was a hero. I just couldn't see it...
The bit where Peter collapses after stopping the train. "He's just a kid! No older than my son!"
The passengers sticking up for him when Doc Ock comes back. "You wanna get to him, you gotta go through me."
The climax, where Doctor Octopus takes apart the reactor, stares up at it, and says "I will not die a monster." Doesn't help that one of the next shots is the reactor floating to the bottom of the sea, Doc Ock drifting slowly with it.
Following the climax, Peter, with his identity now having been exposed to Mary Jane, sits up with her in a huge spider web and tells her the true reason why they can't be together, while expressing a sense of both melancholy and relief now that he doesn't have to hide anything from her. Mary Jane, while understanding, is visibly conflicted and heartbroken as Peter lowers her back down to the ground.