Sure, you don't get 100m² for 500 warm. That's your business, of course. It's true that there are no guarantees for any relationship, whether married or not. The fact that you are considering this is already good; the question is to what extent the "risk" is already present. You won't be able to keep the house alone in the long run if your parents don't help you. I am just imagining it too, at some point, hopefully in the distant future, you will have two houses on one property. What will you do with the other house? What condition is it in? Just asking how the whole thing is supposed to look in the more distant future...