You obviously DON'T trust him; otherwise you wouldn't have felt the need to check up on him. But there's nothing wrong with not completely trusting him. Trust is something that grows in a relationship. Face it, when you fall in love with someone they don't automatically become a perfect person. Until you know each other really well and have been together for a long time, you don't know how deserving he is of your trust. But that doesn't mean that you should run around like a detective, double-checking everything he says.

You're a little insecure and you fear that he will find someone better and dump you. You don't have any evidence of this, but you investigate anyway. In the future, learn to tell the difference between a fear that's coming from your insecurities and a fear that's based on his behavior. Don't assume the worst every time he does something with another girl.

What's done is done. Tell him you're sorry and that you're working on learning to trust him. If he's a good guy, he'll understand.