Lots of men pretend to be ok with no children, but then they hit 40+

Not my personal experience, just something I've observed so many times. I obviously don't know every couple's dynamics, but it's interesting how so many men (i know/I've heard of) aged until ~40y.o. and as they break up they engage with a 25/30y.o. woman and make a child soon after.

It's got to a point that when I see a childless couple past thirties, I automatically think the man would like kids but the woman doesn't, and he'll either leave her in a while or resent her forever.

Anyone thinks that too?