Personally, my problem isn't about Halsin being poly. My main problem (apart from how he sort of leads you to believe he wants something deeper than what he ultimately gives you) is about how he tells you to share your heart with others because he doesn't want to hoard you to himself, but doesn't even give you an option to say "No, I don't want that. I only want you too."

If he can say "I only want you", then I should be able to say the same thing to him. If he's poly and want to roam and whatever, fine, Tav can accept that, but that doesn't mean he should coerce them into doing the same thing.