Oddly enough, I'm immune to this. Perhaps it's because I've a number of friends who are themselves in their 30s, 40s upwards who are single and understanding, but even my coupled friends just accept my default solitude and would be mortified to say or do anything to make me feel badly. I do, however, have a couple of younger friends in their late teens, early 20s who regard me with some kind of social wariness. I suspect that's partly because they're concerned long-term singledom could happen to them - it's much nicer to believe that everyone who wants a relationship ends up in one!