I wonder about a life insurance policy as a 2nd motive?
I think he is one of these empty people who can't truly bond with anyone, can't feel deep love, nor can he see the value of others beyond what they can do for him.
Men almost never leave (or worse) their girlfriend or wife unless they have found someone new, so there is probably a girlfriend.
I hope people will give her grace unless it becomes clear she knew anything, because he probably told her something like he was getting ready for a divorce and just trying to ease the transition for his daughters.