I think part of the problem with some of Tav's facial expressions stems from the fact that there are two valid interpretations (at least) of the romance with the Ascendant. One is that Tav was naive, expected Astarion to remain unchanged, and essentially feels duped/trapped in a relationship as his spawn. The game certainly provides dialogue options to support this. However, there's an equally valid way to roleplay it in which Tav made their devil's bargain happily, accepts the power structure, and enjoys how domineering the Ascendant is.
I see they made yet another modification to accomodate the trapped Tav roleplay, because in this new epilogue scene Tav looks sad when the dialogue options show up after Astarion's monologue. Like they're preparing to break up with him. In the previous patch they looked neutral.
