I found this excerpt from an article about friendlationships called "Who's on First Base?". This is a subject that is near, but not really dear to my heart.

"Anyway, we were almost done when she said something about how we've known each other for almost two years. I said yes. She said we've had a lot of fun together. I said yes. And then she said some other stuff, I don't remember what — you can't listen to everything a girl says or it would wear you out. I think I must have said yes to that too, which was probably a mistake. The next thing I knew, she was talking about how a girl needs a commitment or something. And I guess it took a few minutes for what she was saying to sink in, and I asked 'What do you mean?' And she said 'commitment' and spelled the word. And I said 'It's not like we've been dating or anything.' And she said 'What do you call it when we've been seeing each other exclusively for two years?' And I said 'What do you mean exclusively? I do things together with lots of other people.' And she said 'Not with other girls you don't' and I said 'Girls and guys both' and she said 'What girls?' And I said I couldn't think of any and she asked me why I was holding back and I said I didn't know what she was talking about and then all of a sudden she was crying and she left the table and the waiter brought the check and he looked at me like I was dogmeat and I couldn't find her and so I went home, and I keep trying to phone her but she won't return my calls and it's all I can — I mean I — well — "
He looked embarrassed and took a deep breath. "So that's why I say she changed the rules."