Who’s in the wrong? Neighbours and fences

[PrettyPleaseXo]

Neighbour 1 tree falls through fence and breaks it. Neighbour 2 can’t get fence fixed until the tree is removed. Neighbour 1 gets tree removed after a few months but forgets to tell neighbour 2 and it’s the fence at the end of a big garden so not easily seen. Dog of neighbour 1 escapes through fence which is broken and goes missing.
does neighbour 1 have the moral right to be pissed off at neighbour 2?
Im on the other side of neighbour 2 and don’t see how it’s their fault but it’s sparked wars

Everything in this is neighbour 1's fault

They were responsible for the tree. They were responsible for its removal. They were responsible for repairing the fence that their tree damaged. They were responsible for containing their dog, regardless of neighbour 2's ownership of the fence. (Neighbour 2 could get up one morning and take down the entire fence, if it's on their land, and neighbour 1 would have no recourse other than to build their own fence on their own land.

I feel sorry for the poor little dog though