aio: should I forgive my boyfriend for this?

Well, to keep it short, my boyfriend and I have been together since we were 12, and now we're 17, almost 18. But he told me that when he was 13, he had feelings for another girl he went to school with, and they kind of flirted, but it never went beyond that (according to him, but he has no proof because he panicked and deleted everything when it happened).

He shows me that he loves me, and I've been tormenting myself over this, but at the same time, I feel kind of dumb for making such a big deal out of something that happened when we were 13.

Do you think he's changed and that we can be okay? Should I forgive him? After all, we were pretty young when this happened, and honestly, we really love each other.