Michael Corleone is often thought of as a poor husband and father. He tried to be like his father Don Vito but it just didn't work out. Sure he loved his kids but it just wasn't enough. In the end his family is a mess.
How come Kaye never gets any of the blame for this? Seriously.
Keep in mind that Kaye was Michael's second choice (in fact second wife). If Appolonia had lived - do you think Michael would have had so many family problems? Do you think Appolonia would have ever had an abortion? Divorced Michael? I don't think so.
Maybe the real lesson to be learned from the Godfather trilogy is to not marry a WASP.