I don't like him as much as I thought I did

And the question is.?

Many girls flirt while with boyfriends, most guys are used to it. Flirt all that you want but be clear to the other guys that you're NOT on the market at this time.

If you get swept off of your feet with someone new then that's another story.

Good luck.

I'm not sure what your question is, but let me just say one thing. If you are naturally a flirtatious person, which you seem to be, and you always have lots of guy friends. DON'T CHANGE. Not just because you are in a relationship. I've always been one of those girls that gets along way better with guys than with girls. I've dated some guys who didn't like that, would get jealous, act territorial, etc. All I ever did was get a new boyfriend because it's too much a part of who I am to change. If you ditch all your guy friends and stop flirting for a new guy and actually stay together for some time, what is going to happen when that innate part of your personality starts to come out again?

I just learned a long time ago that I needed to find me a guy who was ok with it. You need to do the same in my opinion.