Romance probably do a "better" ending for every character, because you can "feel" that Tav helps the romanced character
(like Tav and Karlach go together to Avernus is 100% better than let her go there alone)
Unfortunately without proper epilogs we don't see far to the future which will definetly helps us to better understand if the so called good ending was really good or if only looks good
(Did eventually Karlach and Tav find the cure in Avernus? Or died Astarion 10 seconds later when the sun started to burn him?)
I think that is the exact reason why epilogs are so important for RPG players, because they build relationships with companions and they want to know how the party members are doing ather the game ends.
