In literature the vampire bite is often seen as sexual and intimate, especially in the more cheesy twilightesque novels, so this is indeed a valid interpretation of Astarions bite scene.
Swen literally explained it as such, too. I am *so* killing him prior to sleeping in my camp. Bites I can handle, lurching dudes doing creepy sexy stuff whilst I sleep I cannot. Astarion is dead ever playthrough until he's my mc.
