As the title says, both myself and a close friend have experienced this recently.
In my case, ex was so sure he didn't want kids that he had a vasectomy at the age of 30. I was 27 at the time and unsure how I felt about having children. We eventually split a couple of years later but he was emotionally stunted (the most tactful way I can put it) and he totally blindsided me with the breakup which was so traumatic at the time. We lived together, were making plans to get married, etc, and he just left one day completely out of the blue. Like he set off a bomb in my life.
Several years later, I'm engaged to an amazing man, and the relationship is infinitely better than the one I had with my ex. However I've just found out his new partner is six months pregnant and it has really thrown me.
I'm 100% over my ex, though I will probably always carry some residual trauma over the way he treated me in the breakup. It has sadly made it much more difficult for me to trust people. I'm so glad we're not together and that I'm with a kind, loving man. I haven't yet felt any great desire for children and will possibly remain childfree, though I still have time to make that decision.
So why does this get to me so much? I don't want him, or his life, but it hurts that he's doing something with another woman that he was adamant he wouldn't do with me.
My friend has also gone through this, she ended a six year relationship because her partner told her he didn't want children. Not long after, he's expecting a baby with his new girlfriend.
Anyone been through this? It's just such a headfuck, and I honestly hate that I'm giving this any thought at all.