In all the developer notes, even when AA grabbed Tav by the neck - they BOTH enjoyed it. On the part of an AA fan, asking to leave the emotion of fear is a shot in the face to yourself.
I will agree that no dev notes have ever specified Tav's feelings to be negative, but if we're going that route- there are devnotes that don't favour the relationship at all, on Astarion's side, at least (the notes for Neil, I mean). So, by devnotes specifically, there is a basis for a more negative aspect to the relationship. There are other things more in-game than devnotes here I'd discuss in regards to that idea being present or not but I feel like the disagreements there would just be circular, so let's just agree to disagree.
You disagree people who enjoy angst have any business enjoying the route: fine, you can think there's no angst, but I also dislike the idea people can only enjoy stuff if it's presented in a self-indulgent positive way (which is what I think you're implying by that last sentence). I don't feel shot in the face by the idea that relationship might be less than ideal, because I'm not Tav, and I don't care about what happens to my Tav because he's not real (I don't support the inclusion of Tav's face in the kisses because their execution was very silly and nonsensical, but I'm addressing the sentiment in general, bear with me) I know a lot of people, the overwhelming majority, have felt very hurt by it and disagree with that narrative, but it is also a way too confident statement to say that any true AA fan should feel very hurt by this narrative. We are not a monolith. It'd be fair to say that the way we approach the character is so different we might as well be two different types of fans in how we approach and enjoy the content, but we enjoy the same character nonetheless, albeit in different way.
