OP, how is the MH of your DH?
As a home owner I have had six neighbours over 25 years. Two have been a problem.
One neighbour started up after ten years of little contact and no previous bad feeling, she suddenly started bullying me about a pretty average garden, she blamed me for her dog digging in her garden and all sorts of weird stuff, it turned out she developed MH issues because her children all moved out.
The other common issue with both neighbours is that they are control freaks who are all uptight, they are perfectionists who like sterility and the sort of person I normally avoid in life.
Neighbour two has nothing green its all paved and gravel front, side and back. They are very selfish people, anti social with music/party, barking dog, wild children, hit the children shout at them, this is all done inside and I am the only attached neighbour who can hear, outside they behave as if perfect and they are nice to others. They damage my property on purpose whilst they're property looks perfect and block drains too, only I am behind them in drainage.
They swore at me, came into my garden by lifting the fence panel and chopped my shrub, I caught them, the pair of them said they didn't like it and demanded to "sort out my garden" I told them where to go. I actually think they are like my previous neighbour - in need of MH support. I have anxiety and depression myself what these people have is something else - maybe intrusive thoughts/OCD that needs treatment, rather than bullying neighbours?
I would avoid you and your DH like the plague forever more if he said what he is planning to say - if I was your neighbour.