Oh for the rewind button Loiralei alluded to in the first comment! In the absence of one, however, the best you can do is to have an honest discussion about what you want from Mr. Man. It seems rare that women land the “you’re my exclusive girlfriend” right out of the gate from men; an exchange of words is usually required–and sometimes several exchanges. If you don’t speak up for yourself, no one else will. And if what he wants doesn’t line up with your relationship desires, be prepared to walk (and mean it).
If he wants you and only you, he will do whatever is necessary to have you. Good luck!