Harry is someone who feels a tremendous amount of guilt over being alive. He has never gotten over the fact that his parents died for him. His mother would still be alive if she stepped aside. And through the years, numerous people have risked their lives for him. And even when they don't risk their life for him, like with the people who fought Voldemort and died, if they're close to him, he will still feel guilt.
If you solely watched the movies and never got to experience the pure joy that is book Hermione, you wouldn't know what an absolute menace she is. Sure, she may seem like a sweet little nerd at first. But get on her bad side, and she's not above committing war crimes to put you in your place.