It's because people like to judge everything other people do based on their own ideas of a "perfect" life.

I'm not in the same situation, but I had four kids between 25-29. I got judged for how many kids I had (because dont you know that 2 is the perfect number), how close together I had them (because they should be 2.5 years apart you know) and because i was so young looking (drinking age here is 18, I got ID'd until I was 30).

Right after baby number four my neighbor asked if we were the next Duggars. I laughed on the outside because on the inside I pictured decking him. Lol.

There is nothing wrong with being single at 30 or 40 or 50 or 60 and so on. They should respect that it's your life and none of their business.