maybe he is mentally ill. in front of the kids, and then trying to throw her overboard?
He filed for bankruptcy, so money problems. My guess is he was planning on suing the cruise line for her 'accidental death'.
I’m sure the last part was to hide the evidence. He definitely was not in the right mental state for even committing the crime, much less in front of his children, but they go away on an anniversary trip and this happens? My guess again is all 3 (drugs, alcohol, cheating).