Neighbor has erected a 180cm high fence without final coordination

Hello everyone,
we are currently building our house in a new development area (in NRW). One of our neighbors had started well before us and is now working on the garden design. Two months ago, he approached us regarding a fence (200cm) between our properties; he would put it up and split the costs 50/50. In the personal conversation, we agreed that cost sharing is okay, but we still needed to discuss the fence further.
The next day I sent him a WhatsApp message:
"Hello XXX, thanks for your initiative regarding a fence. Splitting the costs 50/50 is okay; we just need to agree on the fence. Basically, we agree with the proposed welded wire fence also for cost reasons. However, we would like the fence not to be too high (2m is too high for us). We can discuss this in person. I am also happy to help with the assembly. Regards"
There was never a response to this message (Reason: I had no time to reply - for 6 weeks?)
Over the weekend, we were again at the house, and the neighbor had mounted fence posts at 180 without any further consultation. The fence posts are on his side (and embedded in concrete partly on our side), the fence panels will be directly on the boundary.
My desired fence height is 120cm and then palisade trees on our side. As a compromise, I would be willing to go higher. I am used to agreeing before doing something directly on the boundary.
Our dear neighbor says, "I don't care what you want; then I'll pay myself and go ahead with my plan."
How would you proceed?

So the first question is whether you just accept it as it is to avoid causing trouble with the neighbor, or whether you check what is actually allowed and then possibly "cause trouble"!?

The question is first of all, who is responsible for the enclosure at this point and what is allowed up to which height. This is usually found, I think, in the state building code, but I believe 1.80m should still be covered (but not necessarily). Whether he has to coordinate with you or not probably depends on who "has to" enclose there. But as I said, that always means you might cause trouble with the neighbor if necessary.

Whether it is not better to let him do his thing and then simply put something in front of the fence accordingly, that is for you to decide. Of course, if he just goes ahead with his thing, then I would at least keep my feet still regarding involvement at first.

I am familiar with the fact that people coordinate before doing something directly on the border.

It would be beneficial for the neighborhood. As long as he stays on his side and the fence is permissible according to the development plan and state building regulations, he can do whatever he wants. Concrete foundations on your side are then not allowed. In this case, I would not participate financially.

Hi, here are the sections from the development plan. I had taken from a brochure of the Justice Department NRW that up to 120cm everything is okay, higher requires the neighbor's consent, or is this misinterpreted?

As always in such cases. The fence is now there, and if you want it gone, you can't avoid stress with the neighbor. Whether it's worth it to you, you have to decide yourself.

By the way, I understood it as follows: a fence that stands exactly on the boundary or whose foundations even extend onto your property belongs half to you, regardless of who paid for it.

You also have to accept that something like this is a compromise. Your preference might be 1.2m, but that doesn't necessarily have to be the neighbor's preference.

I will also plant a hedge for the neighbor that will be higher than 1.2m. Because I have no desire for people to constantly look into my garden.

my compromise would also be 160. at 180 you feel like you are in prison (or at least that's how I imagine it)