At the end of the eighth stage, Vincent swears an oath to Katherine to be faithful again and to never leave her, even jumping down from the doorway to safety to save her.
Even better, if you get the True Katherine ending, Vincent asks Katherine to come back to him after the earlier breakup, and at the same time proposes to her, saying he is nothing without her. Katherine accepts, and it skips to a few months to their wedding in the Stray Sheep. Orlando gets back with his wife, Toby isn't really bothered that Erica was once known as Eric, Jonny decides to start looking for a soulmate, and everyone else is happy. The ending ends with Vincent and Katherine sharing a kiss and telling each other they love each other.
The moment you can finally text four simple words to Katherine if you're going down that route is simple, but poignant. "I love you, Katherine."
In the Bad Katherine ending, there's a good one as well. After all the trouble he goes through, Katherine rebuffs Vincent. Immediately afterwards, Vincent collapses into unconsciousness, not having slept for a week. After trying to cheer him up and then making fun of him for sleeping, Johnny and Orlando take their seats next to him and watch over him as he sleeps.
The sweet little hug they share after Vincent asks Catherine to marry him. D'awww...
The conversations that you have with the people you save on the last day are pretty warm and fuzzy: Justin remembers when he used to write how much he enjoyed it, and decides to write about the nightmares to save other people, after thanking you for helping him, saying that he would be dead if it wasn't for you. Daniel and Anna get back together and decide to run away with each other, Daniel deciding that all of his power and money is meaningless without her. Morgan still goes after the man who killed his wife, but to make him atone instead of killing him, and gives up drinking. Archie manages to move on from his trauma caused by his mom, and decides to start a normal family, while Todd stops being a womanizing Jerkass and goes back to his wife, not wanting to end up like his abusive dad. More prominent if you get them all in the same play through.
The Neutral/Freedom ending, particularly the True version. Vincent decides to choose neither girl, realizing that he's just not ready for commitment. He hangs out with his buddies, bets on a wrestling match, and wins, and one of the final cutscenes shows him pursuing his dream of space travel. His joyful smile and contentment seals it.
Todd and Archie's conversations in and out of the nightmare are heartwarming if you talk to them. At one point in the nightmare, Archie talks about his problems with his mother and women to Vincent with Todd nearby. Todd says "You Idiot! Why didn't you tell me sooner? I could've helped you." The way Todd cares about Archie is heartwarming. Then in the real world, when Archie confesses to sleeping with Todd's wife, Todd automatically forgives him without any hesitation.
Hearing the random sheep talk to Vincent about how he inspires them to keep climbing and how he's helping others and cheering them on rather than being self-centered is rather heartwarming.
Catherine's father gets one in the good and true ending when he tells Catherine that she promised to play video games with him that night. Even though he is/was the Plenopotentiary of the underworld, he still loves his little girl very much.