I come from India, where the culture is a little more conservative than in the West. I am a woman dating a woman (Let's call her D), currently in the US. My girlfriend's roommate's parents recently came to visit her in the US, and I was over at her place. Since I knew they were coming, I pitched in to help with the cooking/cleaning activities and hung out with them too, since I often hang out at my GF's house and her roommates (Let's call them A).
While her parents were very nice to me and conversing, they wanted to know how I knew D. In Indian society, dating is still a little new, and one would not generally introduce one's significant other to a friend's parents even in a heterosexual relationship. I was introduced as her friend. Her parents, however, were confused as to how we met and ended up being good friends, since we both go to different schools here in the US. I brushed it off by saying that we had common friends and had attended a few science events.
They returned the next weekend, and I hung out with my girlfriend again, as I do over weekends. We all had breakfast/lunch at home. They all wanted to go shopping after, and I was planning to head home, not wanting to intrude on their activity. However, my girlfriend wasn't feeling very well, so I decided to stay at her house with her while they (roommates and parents) all went out.
D's roommate told us when they came back, that the parents had a lot of questions about how exactly I know D, why I spend so much time at home with her, whether I come everyday when I live far away, and whether D has a boyfriend. This made both of us a little uncomfortable, especially when D's roommate asked us to come up with names and some story for how we know each other.
How do I gracefully indicate that while I respect them, they are not our parents and really have no business having to know the details of where and how we met and how we know each other, or have a problem with how much time I spend with D? In general as well, when I don't want to go into the whole 'D is my girlfriend' and have to deal with potential homophobia or shocked faces, how do I get people to be satisfied with 'I'm a friend of D's' and not have to answer detailed questions of how and why?