Am I being a stroppy princess?

I think that is very reasonable, and to be honest, despite the relationship being good, this would be a dealbreaker for me - he's got a great life in your home and a nice nest egg from the sale of his. A relationship is about what two people want, not what one wants. If he is happy to live in a small space he'd be welcome to move out into his own small space.

Of course he doesn’t want to move. Why should he start paying a mortgage when he doesn’t have to?!

This.
Control your own home ownership - where it is, how big it is and who shares it with you..
Save a deposit to upgrade or even invest in an extra apartment.

I don't understand why people do this to their children. "Blending" is bad enough when you actually have room, but forcing them in uncomfortably close proximity with some bloke and his kid? Ugh.

If you're not happy with your living arrangements, and he's not financially tied in (so doesn't have a day in what YOU do with YOUR money), then why not just buy a bigger house on your own. Then he can decide to move with you or leave and get somewhere for himself - assuming he'd move with you as your relationship is otherwise happy. Would he be happy doing that and increasing his contribution?

OP, he really has it all set up nicely.
You have provided a home for him and his child without any commitment from him, just his weekly contribution.

For this you and your girls are jammed into a tiny house.
What exactly are you getting out of this?
Its clear what he is.

Your children are the losers.
They have already lost enough haven't they?

The house is too small and you are clearly putting him and his son ahead of your own girls.
That's so wrong.

You are a convenience is my guess.
Time to have a hard think about your girls and put them first.

This man is putting himself and what is easiest for him and his son first.

Women need to be far more wary of men so quick to move in.

The real losers here are your children.

Yes he has the box room.

Does his son live with you?

Even if so it might not be that long before kids are of to Uni/moving away.

I'd probably be thinking more about planning for a comfortable/early retirement!

You are not being a stroppy princess at all.

Buy a bigger house now that you can afford it if you wish, why not- you’ve worked hard for it. It would be a very positive thing to do for you and your children. A good investment.

But don’t allow anybody except your own two children to piggy back ride along on your aspirations, hard work and career progression. Do it for the three of you, nobody else.

If he loves your house so much and is comfortable there, he can buy it from you for himself and his child while you move up the housing ladder as planned.

Sounds as if he doesn’t share your dreams OP, but is maybe using you to hitch himself up a notch on his own finances while you and your children are suddenly cramped for space.

Maybe he genuinely can’t afford to support himself or to move, maybe he’s not as committed as you hoped, maybe he’s a user. Impossible to say but as it is, I think you should put yourself and your two DC first. Blending two families into a one family house isn’t ideal at all and limited space must feel claustrophobic.
You would be unreasonable not to help yourself and your children to something better such a bedroom each, if you can afford it comfortably.

Don’t wait two years or so for him to agree. Do it now or as soon as you can afford to do it. Do it for yourselves. Don’t get side-tracked by him.
You can’t allow him to scupper your future plans. He isn’t on your team as fully as you hoped.

You are not being a stroppy princess, but I think , from your last post, you may be realising that this prince you moved in, is taking advantage.

Tell him you need more space; the easiest way to achieve that is for him to move out.

But honestly, I would be in no hurry to share a mortgage with him, or any partner, while I was earning well and looking after my own dc.

I'd be really interested to know how much he's contributing. Is it really "fair"?

He's got a great deal here. Living rent/mortgage free with no real commitment. Meanwhile the equity from his house sale could be in savings/investments earning him thousands a year.

I'm surprised he's happy for his child to be squashed into a tiny box room. (How much longer can that realistically last)

To me, it's clear he doesn't want to commit himself to you in any meaningful way. I'd be very wary of tying yourself to him financially

I agree with those saying don’t pool finances. I’d investigate what I could get myself with a slightly bigger mortgage (maybe a bit of a do-er upper, maybe same size but room to extend). You could really regret mixing finances and be worse off than before if you’re not very careful.

It would, but having to sell would be the likely outcome if you split up. You’re happy now but breakups do happen.
His son living in a box room should be a concern as he gets older.

Did I mis the post about your children's wishes? You must have talked about it even if you have not asked them directly?

Well tell him either we're moving to a bigger place with joint mortgage or he moves out.
He sounds like a bit of a freeloader. He must have a load of money sitting around from his
house sale? If he doesn't then something gone seriously awry and he is only at yours for a free roof over his head.

Every house I’ve ever lived in has a box room, and it’s always counted as a bedroom. Don’t get me wrong, rereading what I’ve wrote, it sounds disparaging that OP wants to move. I think it’s fine to want a nicer house especially when you’re used to it, but it’s hardly overcrowding and we don’t know her DP is a villain. He could be paying half of all the costs including the mortgage but they’re splitting it in to bills vs mortgage to protect OPs asset.

Just seems like everyone’s jumping to conclusions that paint OP as either a neglectful mum, or a victim of a cocklodger. She’s not saying that what he is.

So I am just reading the threads and can't quite understand. You are happy with your current house for you and your 2 DC. You want a bigger house again (nothing wrong with that BTW) but this is really only to accommodate your DP and his DC, otherwise you would have been happy to stay where you are? So, effectively you are buying a bigger house for him? So will he be contributing to the fees and potential Stamp duty costs for you to do this? But then still not taking on any % of the he mortgage or bills, just food. if you want to move house then do it because you want a bigger house, not so that you have more space for them?

Is he really contributing fairly?

Personally, I would buy a bigger house for me and my dcs without his input. And make sure that my dcs' inheritance was protected entirely.

You should do what you want. You've worked hard, succeeded professionally and shouldn't be held back in any way.

You sound like a very generous woman - just be very careful with that. Whilst you have a good relationship right now, if he were asked to step up and contribute equally to for example, a new property, how would he react? Could be interesting to see.

Also at risk of derailing the thread, I just wanted to say bloody well done to you for rising from the ashes of a divorce. Can I ask what your profession is? I am struggling to find my way after a financially devastating divorce.

Yeah I just don’t understand why you moved this bloke and his child into your home?

How long is soon? This is years…

Did he have his fingers burnt in the past OP with jointly owning and then separating?

It might just be he doesn't want the idea of that being a potential and all the messiness of having to split financials.

Either way sitting down with him and having a chat is a good idea to understand his view point. I would also say at the moment your in a protected position it's your house!

Beetr00 has nailed it.