Financing after separation, what happens next?

Oh, if I got the chance to buy a 150k EUR car for 50k EUR (legally), I would somehow try it even if I then sold it for 99k EUR.

But that of course assumes that you can get it that much cheaper. Currently, the situation is more like a house being built for (let's say) 600k, which might be worth 550k or 600k or 650k in a year. Or if things go really badly, it sits on the internet for a year and then sells for 500k because no buyer can be found due to recession and rising interest rates.
As the original poster, I would only build if the house can sustain itself. And in that case, I would also immediately cut the girlfriend out completely.

The emotional and mental damage caused by the stress during the construction period would be far too great for me to go through with it. Financial aspects aside. I believe building a house is stressful and pressure-packed enough as it is – to then tackle it as a separated couple, I don't know. Better to pull the plug now with some loss – that can also be a new beginning. Whatever you decide, think of your health and take care of yourself. All the best during what is surely a very challenging time!

but it only works if you play poker and don’t let others see your cards.

that's what I mean by "individual "negotiation skills"" ;)

Quickly check how to best get out of the contracts and minimize the damage. No matter how beautiful the dream of owning a home seems, it is not worth financially overextending yourself and then someone else takes half…

So before I start yelling "cancel"... how much do you have in your account at the end of the month and what is your monthly repayment? Maybe you should also present the entire project here. Maybe you can handle it alone after all, maybe not, and the whole project is badly calculated.
With the interest rates, I would think three times before dissolving, especially if you really want the house.

But it has to be clarified that the lady is removed from contracts and the land register. Otherwise, he’s pouring his money in alone and she will come around eventually wanting her half.

But it must be clarified that the lady is removed from contracts and the land register. Otherwise, he puts in his money alone and then she comes around and wants her half.

Something similar happened to a friend of mine. He built a house with his long-term partner (not married), she was registered with 50% in the land register. However, he paid for EVERYTHING. Well – after the separation, he then had to pay her half of the house that he had paid for completely... It was a very painful lesson for him.