Cheating

I don't trust myself. For now, I do, but I'm worried that once I go to uni in September, I'll be less loyal to my boyfriend. Obviously, I don't want to cheat, but I just don't know how to trust myself. Plus, everyone has different definitions of cheating, some people think flirting is cheating, and some people think others are flirting when they're just being friendly. This combo of factors worries me. I don't want to cheat, I have no intention of cheating, but how do I trust myself? Help pls.