I need help!!!... plz?

OK.. HERE'S THE DEAL.. IM LYK SOO IN LOVE WITH THIS AND EVERYTHING HAS BEEN GOING FINE UNTIL TODAY WHEN HE JUST STARTS ACTIN ALL WEIRD AS IN EXCESSIVELY TALKING ABOUT .. NOW WE NEVER DID IT. AND I LOVE HIM SO MUCH AND IM PRETTY SURE HE LOVES ME BUT.. IM SO AFRAID THT IF I SLEEP WITH HIM HE'LL JUST LEAVE.. I'VE ASKED HIM ABOUT IT AND HE SAYS THT HE'D NEVER DO THAT TO ME .... BUT ITS HARD TO TRUST GUYS NOWADAYS.. WHAT SHOULD I DO??