dude probably declined because he's already been on 4 dates (5 since he paid for your friend) with you and maybe by now he knows he wants to fukk and isn't trying to go to some brunch/museum/whatever. plus eventhough you invited him, since he started with you on that gentleman tip, he probably thinks you still expect him to insist on paying eventhough you offered. meanwhile my man is probably trying to get some ass from you but too afraid to let his intentions known.