I’ll never tell her.

I was 16, and my girlfriend and I planned on having sex–my first time, not hers–at a party where we were guaranteed a room to stay the night. I showed up to find my girlfriend pissed drunk. I was bummed, but I was so eager to lose my virginity that we had sex anyway. She passed out and I went back downstairs to hang out with friends. At that point I learned from other people there that she had gone down on some other guy in the bathroom before I showed up. The next morning she woke up and asked me if we had sex last night. I was so mortified that I lied and pretended to still be a virgin until we could have sex under more preferred conditions. I never did tell her the truth.