Heck, I'd love to see that in the game! Right now the companions have no reaction at all to the Astarion romance, just one (!) line from Shadowheart at the party, something like "You and Astarion seem to be cozy together..." and that's it. Nor is there any reaction to Tav becoming Astarion's spawn.
For me that scene with SH fired only once, out of all playthroughs. Only Karlach seems to notice an ongoing Astarion-mance in my runs. Freaking weird. I believe banging Astarion BEFORE the party causes some of these bugs...
