After defeating Cazador, Astarion remained quiet for the most part of the day. He was not so responsive, dissociating during the way back to camp. You had to let him stay there, switching with another companion to complete more missions.

Despite being lovers, you figured out he needed all the space he could get for just a while. By the time you came back around evening, he was already on his way to the graveyard, visiting his own grave as he knelt in front of the tombstone in silence.