Girls what would you do, if a guy you find ually attractive tells you he only wants to have wih you..?

What would you do if a guy you met only recently but who you find to be y, (and is cuter than your boyfriend / husband) tries to Bone you? Because he has a girlfriend and he doesnt want a relationship with you ...Sincerly what would you do? would you grab the opportunity, or would you let it slip away?