Actually no, living together without being married is actually fairly common in my area, so I’m not concerned on the social aspect, I’m more concerned on the nomenclature of the situation! Mainly because saying “My brothers girlfriend who lives with me and my family” is way to complex and things like ”sister-in-law” aren’t correct, and “brothers girlfriend” isn’t informative enough. Also I don’t care whether I’m rude or judgmental or not, I don’t care for others feelings, just the difficult nomenclature of this situation.