"Buying a 'transition house' for a few years?"

I would also openly ask what he has in mind. Better to step out of your comfort zone once than to keep searching for another six months or more depending on the region.

That's exactly what I would do too, ask openly or say that you discovered the ad and inquire about what the previous agreement is lacking.

Sorry, wrong lay opinion. Sale of real estate = MANDATORILY notarized. Otherwise, no purchase contract comes into existence. No matter what is agreed privately (in writing). [...] ==> see Building Code

Then please effectively help my "wrong lay opinion" by naming the specific paragraph in the Building Code that in your opinion states that a real estate sale must not only be notarized mandatorily, but before that is not only pending, and completely inconsequential empty talk. In my opinion, the unrevoked agreement to carry out the sales act cannot be broken without further ado. If I am wrong, I am happy to be corrected, but I do not consider it appropriate to peruse the entire Building Code.

Well, what can you say – there are just incredibly beautiful moments when searching for a house. For example, when you have agreed on a price with the seller (we made an offer, he made a counteroffer, we agreed – all in writing by email) and the house almost simultaneously appears on the usual portals after our agreement. That probably settles it… there’s definitely someone who will pay the 5000€ difference to the "negotiation basis" price.

That sounds very unpleasant, but it could also be a misunderstanding. Maybe several people were simply "tinkering" with the sales process and did not yet know that the house had already been sold. I’m keeping my fingers crossed for you. Apart from your specific case, I can say that I still appreciate having nothing to do with agents/sellers etc. anymore. The worst experiences with people I have had were connected to plots of land and house searches.

If I am wrong, I am happy to be corrected, but I do not consider it appropriate to browse through the entire Building Code.

Now you're being picky ;)

§311b paragraph 1
"(1) A contract by which one party undertakes to transfer or acquire ownership of a property requires notarization."

Addition §125, that a purchase contract is void if the legal formal requirements are not met.
"A legal transaction that lacks the form prescribed by law is void. The lack of the form specified by the legal transaction also results in nullity, as a rule."

You're welcome!

§311b paragraph 1 "(1) A contract by which one party undertakes to transfer or acquire ownership of a property requires notarization."

I read this only as a legal requirement for the execution of the legal transaction before a notary, in

"A legal transaction that lacks the form prescribed by law is void. The lack of the form required by the legal transaction generally also results in nullity."

I merely recognize a threat of nullity (to be read as an urgent advice for the immediate cure of the pending issue), but not as a carte blanche to break a promise to carry out the legal transaction together. From my understanding, the statutory obligation to involve the notary as a "witness" does not imply that acting contrary to the engagement kiss would go without consequences.

From my understanding, the legal requirement to involve the notary as a "witness" does not imply that actions against the engagement kiss would go without consequences.

Well, I wouldn't want to sit with you at the notary either, after the signature there's a wet kiss included for free ….

Unless a written preliminary contract was concluded, where possibly also damages were agreed upon, it remains with declarations of intent by the parties or, to stay with your comparison, "whispered softly in the heat of the moment 'I want to marry you' doesn't even last until the cigarette afterward and is forgotten the next morning."