Growing Up With A Small Penis

I played a lot of sports growing up. I knew early on I had a small penis. But in High School my first serious girlfriend and I were making out and one thing led to another. Well this was the first time she had seen a guys penis and the first time I had seen a girl naked. Anyway we were playing with each other and she stopped after a bit and said, AND I WILL NEVER FORGET THIS, but she said, "why isn't it getting bigger, I thought it was supposed to get big?" I told her I was erect and hard. She was like "all the girls said that a dick will get big when you play with it. I said that's as big as it's ever gotten. She said that the girls must have been lying then. Well.... no they weren't lying. We stayed together through high school. A short time after that she found out that yes, guys with cocks get bigger. She realized while we were dating but never said anything, until Kyle fucked her. It started as a cheating one night stand moment that grew into something more regular like things do at that age. I remember in an argument with her about it she blurted out, "well why cant you fucking get your dick hard like he does?" This went on for a few months until we eventually broke up. I guess you could say I've been a small penis cuckold all my life.