My boyfriend lived with someone several years older than him, from his early 20s to nearly 40. She was divorced with teenage children when they met, he was unmarried with no children.
She didn't want further children, which he accepted that.
I then met him a few years after they broke up. Amicable, he initiated, run it's course sort of thing.
They stay in contact fairly regularly by phone. He used to mention her constantly in conversation for the first year or so we dated, now it will only be perhaps once or twice in conversation. We have been seeing eachother for nearly 3 years now.
I have two young primary age children.
When she visited him with her friend one time at his flat in our early dating days, she glanced at his car and on noticing my child car seats in the back laughed at him about it. He did relay this to me. I don't know why, he must have known I'd find it questionable 
.
He has always insisted it was innocent, a sort of cheeky, bantery response, but I have always felt awkward about it, and a little bit 
. Was she trying to embarrass him?
I don't know why, but it's just one of those passing things I've always wanted to understand, as I don't 'get' it.
He explains that she is a lovely lady and no harm meant, so I will accept that, but if I visited my ex and saw child seats in his car that belonged to his new partner, the last thing I'd do is joke about it. Especially if I'd been the one ultimately responsible for not choosing to have children with him. It would feel a bit smirky.
What was it about?