Movies that understand what relationships are really like

[Orange Green Tea]

What are some movies you think have a realistic understanding of how relationships work?

They don't have to accurately portray them, just show that they actually understand some real qualities.

Here's a few of mine:
(500)Days of Summer
-A lot of people I know always tell me that when they watched it, it was just like they were back in a relationship with someone they loved.

Forgetting Sarah Marshall
-The comedy aside, this film has a fundamental understanding of what goes on in relationships and what happens when two people don't communicate.

Fever Pitch
-Probably one of my favorites. There's a lot going on between them and in the end it's about loving someone for who they are.