I think some people assume that at the end of the day "everyone" wishes they had a family... a lot of elderly people who chose never to start a family (or time just got away from them and it never happened) do have regrets about it. Of course there are many people who do simply decide not to have children and never regret it; my aunt (just turned 70) never had kids and I don't think she has any issue with it. Her and my sister spend a lot of time together (as they both live on an island with an off season population of < 2000) but I don't think she regrets not having her own kids, at all.

However... I can see someone like Nicola not understanding that and believing that it's a hurtful thing to say to ANYONE who never had children. She is self-obsessed and she likes the fact that she is a mum, therefore, she assumes that EVERYONE would like to be a mum.