It sounds like your expectations on your neighbour are way too high. Especially since them doing "their" part on par with your expectations benefits mostly just you.
When your neighbour isn't as invested as you in maintaining the border or has other annoyances you are better off leaving some buffer zone that allows to isolate yourself from the border and whatever road, river, canal, forest or loud or busy place is at the other side.
When your neighbour isn't as invested as you in maintaining the border or has other annoyances you are better off leaving some buffer zone that allows to isolate yourself from the border and whatever road, river, canal, forest or loud or busy place is at the other side.