Don't really know why this series keeps trying to make Kippei sympathetic. End of the day, it was his choice to cheat (TWICE OVER MIND YOU) on his wife and not just get a divorce beforehand. He's not a complex person, he's just an indecisive doormat. He really didn't need additional influences.
Side note: I do find it funny that all for the planning and trickery, the one thing Aoi can't handle is a slap to the face. Power Slap contender she is not...
(not that anyone should be playing that """Sport""")