This should be easy to remember, but I'm having a senior moment.
In the 1980s, potentially early 1990s, I read a very funny book about a man whose wife goes off with the new neighbours on a houseboat and the husband is soon on the hook for killing her. She learns they are swingers, at which point she escapes on a floaty. Meanwhile he's accused of disposing of the body in his college class's meat grinder. Noticing one of the officers having a meat pie, he agrees with them and says he put it in the filling. Eventually everything unwinds and they live happily ever after.
This was a pretty well-known book, at least in the UK. So much so that they turned it into a moderately OK movie, but like so many, the timing just wasn't on.
In any event, does anyone recall the title? I'm looking for some summer reading for a friend and thought they'd like it.