Partner won’t marry me

Yes indeed - in the event of his death he states the children would ‘allow’ me to live there until I sorted something else out. And yes he would want me to continue to pay for it

He would want you to pay the mortgage even AFTER you’d left and ’sorted something else out’?!

Sorry, but what an arse! I would be finding a rental and moving me and my kids out asap.

Tbf I get why he wouldn't want to get married again and then for his kids to not inherit his house. I'd feel the same tbh.

Maybe he considers the money you pay towards his mortgage to be rent?

Anyway, yanbu for leaving. You want completely different things.

Stop putting in to his mortgage from this moment forward, it's absolutely ridiculous! He wants you to pay towards his children's inheritance which basically means nothing for your children when the time comes. I'd draw the line here and move out too

100% op. I sympathise with wanting to leave assets to your dc but he lost me totally at you will pay the mortgage for his dc if he died.

He's protecting his kids, but why aren't you protecting yours? Why pay into an asset that you have no claim on? Yes I would be looking at buying my own house. You want different things.

Both of you are not being unreasonable. You need to put yourself and your children first and leave him now and get security for yourself and your children.
He’s also not being unreasonable by not signing off his children’s inheritance over to you. By paying his mortgage here you mean you’ve been paying like rent to live in his house, because if you didn’t move in with him, you’ll be paying rent where you were before and you won’t expect to have a share of your landlords house just because your rent has been paying his mortgage. That’s just the way he sees your relationship, it’s transactional and not like a family unit.
He’s not stringing you along, he’s made it clear that his children are his priority which is not a bad thing for them but not for you as this just leaves you vulnerable.
There’s no point giving ultimatums, this is how he sees the relationship and you can see this is not what you want so you need to leave him and build a future for you and your children

He is unreasonable to expect you to pay towards a mortgage where you will have no stake on the property. I understand him wanting to ensure his assets go to his children. But that doesn’t have to mean nothing for you. You could own a home together as tenants in common, so you BOTH get to ensure that your respective children inherit.
Did he not make his position on remarriage very clear from the start? There’s nothing wrong with not wanting to get married. But if he future faked, knowing it is what you wanted, that’s wrong. Separating because you want different things is fine. You don’t owe him a relationship,

Why pay to something that is never yours, or you have control over. Seems like he has all the cards and you just keeping paying into his pot. Stop, prioritize you and yours and move on.

He's not your partner.

He's your landlord.

He expects his children to get all the money from your house that he doesn't contribute towards? What about your children? Crazy!

He's been open and honest with you, he won't change his mind and you shouldn't change yours on what you want out of life either. This won't work, no point drawing it out with an ultimatum; at least he hasn't strung you along or kept you sweet with false promises and lies.

YANBU but I do think YABU for being with him for so long knowing he doesn’t want to get married and knowing he isn’t interested in buying a house together.

Do you really want to be married to someone who only buys a house and marries you because you are forcing him too? Let that sink in.

He has made his feelings clear as you say, you both want different things, I don’t see how this is going to work out.

YANBU. Don't compromise. You need to leave

Why did you sign up in the first place? I’d buy my own place in that case, do you have funds in place to do so now? Sounds like he isn’t taking you seriously because you aren’t in a position to negotiate. Worst case scenario, you buy your own place, and then you have an asset to rent/sell/allow your own kids to inherit.

This. You don't sound compatible. You are not aligned in what you both want so now it's time to take separate paths.

Don't leave yourself vulnerable.

You are definitely not being unreasonable

he’s’ been very clear where you stand so it looks like there’s no future

walk away - protect yourself & your DC

YANBU to refuse to pay his mortgage when it leaves you and your DC financially vulnerable.

He wants you to pay the mortgage until the house is sold to benefit his kids and you get nothing?
I've heard it all now

You both want different things which is fine. As sad as it is you're not compatible. I think it's best to cut your losses and leave to live independently.

I would stop contributing to his mortgage, buy my own property and get out. I can understand him wanting his children to inherit his estate, but it sounds as though he wants them to inherit your money as well! You need to put yourself and your own children first.

Look out for yourself OP and if this relationship isn't giving you what you want, walk away. TBH, as he has kids, I don't think he is being unreasonable to not want to marry you and risk their inheritance going to you/your kids. But he is entirely unreasonable to expect you to pay his mortgage after his death, yet have no claim on the property - that is clearly blatantly unfair. So plan for your old age accordingly. Buy your own property. Make sure you have your own good pension provision. And make a will ensuring that your kids get everything.

You're not his priority and as you've said, should something happen to him, you're financially screwed.
Leave him and put yourself and your children first.

Great advise

Don't give him the chance to string you along and say marriage in a couple of years ..
He's had long enough already