I had my first sexual experience with my girlfriend a few months ago. She told me she was a virgin, but after having intercourse, I didn't believe her and was hurt. She didn't seem to be in any pain, there was no bleeding, and there was no hymen. She makes up all these excuses like "not all girls have them." Should I believe her? Is there a sure-fire way of determining whether or not I was her first? It is making me angry. Can you ease my pain?