I'm a couple chapters into this and their dynamic reminds me of that meme of two characters holding hands and ones thinking about them holding hands and the other is thinking about sex
I think this is just plain old regular jealousy. I don't think Andrew is 'obsessed' with Luke, there just isn't a lot of the right communication going on and what we're seeing is Andrew overthinking.
I don't care anymore, I'm just staying for the art, it's so chewy