Not being comfortable with a threesome with sex workers doesn't have much to do with whether someone is polyamorous or not fyi. Especially when that person is uncomfortable even having sex with the person there dating. (spawn astarion is so relieved in *every* scene where you turn down sex with him).
Same with not wanting some people to be your metamour. Like I don't think he referred to it as a need like that in my playthrough when my Tav started a relationship with Halsin. He asked if it was just about him not having sex with me and was ok with it when I said it wasn't.
