Wait, what does he do? I don't remember him doing anything strange after my Tav's rejection. Then again, I stopped having him in my party the moment I reached exceptional approval and then he spent time alone with Orin. He still seemed to be into my chara during the epilogue party.
He will ask to join you with the Drow even if you are not in a relationship as long as he is in the party. Unfortunately there isn't a text-option for "You go have fun Halsin, we'll wait down here."
