Not sure about the hate towards Astarion, but I actually made him my romance character as he was the only one approving of my decisions haha. I like the fact they made him a bit cheeky, posh, sarcastic and charming but I guess for some, these characteristics might come across as 'gay'.
Never had any romance lines with Shadowheart but as someone stated before, she seems bugged or maybe she has a split personality cause she can be sweet and start opening up to me, then she just lashes out at me to say she's just with me to find the cure.
Bug wise, Gale seems to be glitched as well with his camp conversations about his condition. He gets the exclamation mark that he wants to speak to me, just to tell me the same thing that he had already said (even to the progression of finding and GIVING him the artifacts).