Even if you and your husband-to-be are having your third wedding, and even if these nuptials are, like the ones that came before them, doomed to fail spectacularly since you actually have no desire to marry your husband-to-be, it is still important to spend quality time with your in-laws, so it's not wrong, exactly, that Luke and Liz spent a good deal of time today bonding over shared interests and habits.
What is wrong is that they bonded over...being miserable in lives that they never wanted. At an engagement party! What the what?
Liz, to her credit, knew how blatantly inappropriate the conversation was and flashed Luke one of her patented awesome facial expressions when he said...
Luke: He will. I'm very happy for him. I'd like to be happy for you, too, but I...I get the feeling maybe you're not as sure about all this as he is.
(It was very "We're going there? Really? Here? I don't think that's what you want to be doing")
but that didn't stop the douchery.