He’s looking for someone “better” than you. If he thought you were “the one” then he’d be stupid to keep looking when that risks alienating you.

You’ve only gone out twice so, at this point, he doesn’t know you. It’s too soon to ask him to take the ad off the dating site.

But, whatever you do, don’t sleep with him! Better to lose him because you won’t sleep with him than to put out and still lose him.