I remembered a line from the devs before launch how Astarion's romance starts once we allow him to feed on us and that that's just how it works with him. Let's compare it to Gale's (weave scene) and Wyll's (dance scene) romance beginnings, which are clearly romantic and intimate in nature. Although, the bite is without a doubt intimate due to it's physical proximity aspect, there is nothing amorous about it. In fact, throughout the scene Tav looks like they're suffering and struggling to break free. We could argue it's Astarion's first time and he's very hungry and not gentle at all, but then later on, he comments on noticing how we'd enjoyed it and we can actually admit it to be true. The words just don't match the actions.
It seems this scene was designed to be neutral and noncommital so it would work for both friendship and romance paths, and I'd prefer if it did in fact have more suggestive undertones, like with other male romances. I think there should be an extra option where we can select that Tav is feeling excitement with Astarion being suddenly so close to them and finding the whole thing pleasurable. The animation should change then to a more relaxed and sensual one, maybe with Tav putting their hand on his back and him leaning down a bit lower or even straddling Tav during the last persuasion check when he's losing himself in the bloodlust.
If Tav can tell him they enjoyed it, I want to actually see them do that in the scene and not writhe in agony.