I used to not care about vtubers talking about significant others, but my stance has changed a bit. When a vtuber is "in character," then what sort of character are they? Turn on any anime series and see who the characters are. 98% of the time, whether male or female, they are young, attractive and single. Now it's not that nobody can ever try to work outside of those boundaries (I say as someone who has never pretended to not be a boomer), but that's what people expect from anime characters, and to a certain extent it's who your "competition," either vtubers or actual characters in anime, will be. So if you want to be a real anime character and not just a fleshtuber puppeting a model, you stick to the anime character norms and don't acknowledge you have a significant other.
All that being said, I hope that the performers of all vtubers, in real life, find long-lasting and fulfilling relationships with people who love them and treat them right and never acknowledge it on stream. So I don't think of myself as having a unicorn-ish take on this, though maybre you disagree.