My girlfriend wouldn't have sex with me.... how selfish is that?

[Derek]

We were in bed last night and I got an erection in my boxers. She wouldn't have sex with me, claimed she was too tired from work. How selfish is that? I ended having to go take care of it with a Hustler magazine in the bathroom. When I was done, I called her a selfish b***h for not helping me deal with it. She then made some sarcastic remark to me saying "You should probably change your boxers after that as well". She made me sleep on the couch for the rest of the night. It was really uncomfortable too. I mean I'm 23, I think about sex a lot, I mean I can't help it if I get an erection. It isn't fair. What should I do now? She's pretty mad at me.