Not necessarily. He has possibly had an optimistic notion of the future with OP and his children in his mind. He is allowed to be disappointed and even upset that it won’t come to fruition.
Yes, he is allowed to want whatever he wants. However, he has bene pushing this on op for a while. Never picking up that she wasn't happy with it.
Or did pick up on it and just carried on. A partner would have a converstation about what they want and their expectations. Not just keep pushing then on the direction they want. Which is what he has been doing.
Op, I don't think them being a bit older will help. What happens when one is 11 and still having strops because they know their dad caves? Or at 15 he is still playing Disney dad to keep them happy.
What happens when they still know how to play their dad and want to come and stay during the holidays from uni? Or want to come live with you both after a relationship split.
When they get married, your dp wants you there, they don't because they barely know you. Or know that you resented them.
You keep sayings it's down to their age. But I think, like me (so not judging) you have no interest on living your life around someone else's kids especially, when their parenting is making life harder. I have no interest in trying to joint parent with my dp and his ex.
Again, you may be happy never living together, many people are but it doesn't sound like it.
You keep saying no one has loved you like he loves you, but you are edging back although you know, that's not the right thing and that love will turn to dislike.
And tbh, you have no idea what's round the corner. There will be many people out there that you could love just as much, that you love you the same, but have their life in the same place you do.
You are holding on because you think, love wise, you won't get any better. That's just a fear you are