Call it that if you like. I wasn't seeing anyone, as far as I knew you weren't seeing anyone. Sex is fun. I like having fun. It fulfilled a mutual need-- what I thought was a mutual need-- and I didn't expect anyone to get hurt.

Maybe you trust the other people you're seeing, that doesn't mean I do. If you're putting my health at risk I have a right to know.

[Sigh, she knows that's a lame excuse.]