I think Dennis just feels guilty for all the awful things he accidentally does to Mr. Wilson, so is constantly trying to make up for it. However, the attempts tend to cause more accidents, and thus is a continuing cycle. When I was a kid, I used to have a neighbor like Mr. Wilson, which I was also the cause many misadventures with and was caught in that same loop of trying to fixing one problem and causing a new one in turn. I was always acted friendly toward my neighbor to try to not make the situation worse, but mostly I just felt bad for all the stupid things I did to him. Just cause you come off as a monster doesn't mean you actually are one.

That's a nice theory. He is constantly trying to make it up. It makes sense to me.

That's what happens in the sequel, when his grandpa comes to town. He spends more time with him instead of Mr. Wilson.