House purchase - Is our planning working?!

With a tenant like that, who is not even willing to show the apartment, you are buying problems you don't need. Period!

I suspect so too. That's why we decided against the house. We wouldn't be happy with it....

Done everything right, the house will probably still be on the market in about a year if the seller doesn't come to their senses.

For further search: do the parents absolutely have to move in with you? That already severely limits the number of possible properties.
Generally regarding affordability. Your equity is very good, but your husband's income is really not good.
Now have a child who is not 100% healthy (it doesn't have to be anything serious, there are a thousand things that occupy you much more than expected/planned in the first years) and you can't go back to work immediately after parental leave. Any financing collapses immediately, unless you set aside several tens of thousands of euros for such a case.
Overall, it's all doable, but I would maybe try to find something suitable just for you and thereby minimize the financing amount and thus the installment/the risk.

We are just stunned. The house was sold today. Someone submitted the acceptance today. The real estate agent is also confused and said "either the buyer is blind or has too much money." So the house is off the table.

My parents are supposed to move into the house as well. It might sound strange, but it is easier to find a multi-family house than a single-family house here. So that would actually be an advantage in that regard when searching...

And yes, I also see the objection regarding my partner's salary as a criticism. He is changing jobs in August because he simply has more opportunities there. He is starting, however, with 2300 gross, but after half a year there will already be a raise and they are bound to collective agreements (so holiday and Christmas bonuses etc.). At his old company, 2300 was the maximum you could get.

then click on continue to search and your friend should step on it

During the probationary period, unfortunately no one is creditworthy. You will have to be patient now.

We are just stunned. The house was sold today.

My parents are supposed to move into the house as well. It might sound strange, but it is easier to find a multi-family house than a single-family house here. So in that respect, it would actually be an advantage for the search...

Well, at the moment everything is simply being sold due to the low interest rate phase and the simultaneous fear of rising rates. I believe you could even sell a garage as a mini-house cleverly marketed for around €30,000.

By the way, we have exactly the same experience as you regarding the search: we could have had plenty of multi-family houses, which were often even cheaper than the (extremely rare) single-family houses. We didn’t want that, it would have simply been way too big for us. But the search for them is definitely much easier, that’s true.