Dating reel him in
You deserve each other, and you are equals in the relationship. That said, don't make a huge fuss over the little things, but do assert yourself appropriately when a woman comes up to him and you're around.Let her and him know that he is yours, and you want to keep it that way.
Also, it wouldn't hurt to let it be known, once in a while, that you have suitors of your own.
He won't shy away from or discourage the attention, but he will (if he's a decent guy) simply enjoy the attention and not take it any further.
The hardest part about dating a guy like this is seeing his phone constantly light up with flirty texts from ex-loves or interested pursuers and watching women make passes when you are standing directly next to him. How do you handle him, and, more important, how do you keep him focused on your relationship when he's being approached left and right?
Well, even if he's genuinely into you, you run into an ex of his every time you go out and his phone is constantly blowing up with flirty messages. But dating a guy like that is all gravy until, well, you become exclusive with the suave sucker.
I sympathize with you wanting to be the only woman allowed to enjoy him, but in this case you can't have your cake and eat it too.