I believe you need to do some serious soul searching. My opinion is if you are in a declared boyfriend/girlfriend relationship then you take yourself off limits to others regardless of whether or not you actually are in love. What's the point of declaring a relationship if you're not going to be true to that relationship - unless you have an agreement to be open from the very beginning. Anyway, if he's cheated on previous girlfriends (that he hasn't loved) why do you feel you are different than they were? Has he told you he loves you? Some people, even if they love their partner, just can't stay faithful. Sounds like your bf may fall into that category.
So, what are you willing to put up with? Honestly, if he's cheated on you once (and you can say it was only a kiss but it will proceed to more with other women, I'm afraid) he'll cheat again in the future. I don't believe this will be a one time event given his history. If it was me I'd say break up with him.... you can do better (which I do believe) but I don't know him or you so what I say doesn't matter. What do you feel is right? But, I promise this..... if you chose to break up with him you will find someone else!! You will enter that relationship wiser and knowing what you will and won't put up with and recognize the red flags early on.
Best of luck!