matsag on "Women in their mid thirties or above who never married?"

I know a ton of women in the 35+ age range who never married. For instance, at least half of my good friends from HS, I know for a fact they are still single. And they don't even seem to be dating anyone. I know some of them may be deliberately choosing this, they just don't want to marry, but what about the ones who aren't? The clock is running out of time for them to have genetic children. I have to wonder how they feel about this--is it like the despair many of us went through when going through IF? Is it hard for them to be around married women with kids? I am never sure how to handle it, since I don't want to be intrusive and ask them about it, or make insensitive comments. You don't come right out and say "So, why aren't you dating? Do you want kids? Do you want to get married?" Hard subject.
One of my best friends from HS is living nearby now and wrote that she'd love to get together, then no follow through. She has never said that she never wants to get married or have kids so I am assuming she just isn't finding anyone. So is it really uncomfortable for her to be around me and see my kids?