“He was very clear from the start that he wanted children and I told him I was definitely open to it. Which was true. There have been times where we’ve been actively trying and I’ve been happy to, but then life got in the way, illness, parents illness, work stresses, and I just increasingly feel so busy and tired. I’m worried how I would cope to be honest, I realistically don’t know if I have the capacity to have another child without having a breakdown. I’m essentially working two jobs and trying to do the best for my kids. He is great with them and they love him, but has a tendency to check out of family life / interacting with me and the kids when he is having low moments.
The legacy comment just made the whole thing a lot less appealing and it is difficult to discuss the logistics with him. For example when I tried to talk about childcare for when I would return to work if I was on maternity he says my parents and his family…my parents are aging and terminally ill and his family are too far away to travel back and forth every day. But there’s no discussing this with him, he thinks it’ll all just work out and we can rely on other people. It’s like he’s in a dream world and if I want to discuss the realities of a situation I’m just being a party pooper.”
This is very helpful context, OP.
I think your partner is getting a hard time here from you and many posters for having expressed himself a bit clumsily. Having children is about reproduction. For most of us, our children are what will remain of our genes when we have gone. I think that’s what he’s expressing. He’s trying to explain why being a step-parent to your children does not entirely cancel out his wish for his own biological children. You and your ex-husband reproduced and it wasn’t an unselfish act on your part - it was about continuing your and your husband’s genes, even if you totally see your children as their own people separately from you. Which is absolutely fine - the world needs children - but you’re making an artificial distinction between why you had your own children and why he wants them which is unfair to him. Surely you can see that?
So yes, you’ve had your own biological children and you told him you were open to having them with him. You’re rethinking that and you’re absolutely entitled to do so, especially with his artificial hurdles to marriage, but instead of mocking his clumsy turn of phrase it’s appropriate to recognise that you’ve moved the goalposts. He wants something that a great many people want and that you’ve already got.
There are plenty of posts on MN from women whose male partners have changed their mind about having children and they are generally advised not to put a man ahead of children if they’re certain they want them.
A dear friend of mine was in your position. Her partner was great with her children but very much wanted his own. It took several years to work through but, like you, she ultimately felt this was not the right thing for her and eventually the relationship ended because her partner wasn’t willing to forego the possibility of having his own children.
No-one should have children they don’t want to have, and your reasons for your re-think are completely valid. But it seems a bit cruel to mock him for wanting something that you already have.
It sounds to me like your needs and wants may be becoming incompatible. He may not want to commit to you in marriage if doing so means he foregoes the possibility of having his own children. You very reasonably don’t want to more children without marriage and may not want them anyway.