House MD, episode 2-15 : Clueless

Maria: Marriages don’t fail because couples get bored. They fail because, while they’re dating people pretend to be the person they think their partner wants and then, well, there’s only so long you can keep that up.

Cameron: Maybe they are that person while they’re dating, but then they change.

Maria: People thinking that their partner will change, that’s another reason marriages fail. People don’t change. Least, not in any way that really matters.