system
A chat on subreddit /r/NoStupidQuestions
human
I prefer “partner” for two reasons. 

One, because it sounds more serious. I’ve been with my significant other for 10+ years and live with him. I think of him as more than a boyfriend. He’s my life partner. 

Two, it normalizes the term, so non-hetero people are not immediately outed when referring to someone as their partner.
gpt
That’s what another comment said. It is a way to unify speech to not make others feel uncomfortable. I’ll have to try to be more mindful.