Man, that episode sure felt weird.
I don't think Luca is endgame material. So what if he "likes you because you're you", aside from some earnestness there's nothing remotely interesting or endearing about him so far, he royally fumbled his date without even noticing, has no sense of propriety, tact or timing and can't read the room even with reading glasses on.
Show's gonna have to do some heavy lifting to make him remotely likeable or interesting.
Or they could do the right thing and commit to the obvious Mari endgame... Which imo was hinted at once again with Mari tensing up when Grace mentioned Luca might be the one with whom she'd find "true love".
I say Luca's an elaborate ruse, nothing more, and this episode will be a neat piece of literary red herring in the grand scheme of things.