I'm still working my way toward the new epilogue (starting with my Gale run), but I'm a bit disappointed to learn:

if you've "only" befriended Astarion, apparently you don't see him at all between him running off at the docks and the epilogue party. But other companions apparently manage to find him! That's sad, all my Tavs would've tried to find him and offer any aid or comfort they could.