I think a big part of why his ending is the way it is is because Larian diddnt expect anyone to be solomancing him seriously. He was made to be the third party in an already established romance, to be tossed aside when hes nonlonger convinient for sex. Why WOULD anyone wanna go be with Halsin when they can go be with SH or Astarion if theyve chosen the nonmono route? And why wouldnt you do the nonmono route? Thats his role they made for him, even though thats not really what the people who wanted him added were really asking for.
