If the waifus are 3/4 real goddesses, they wouldn't give a shit about monogami. Humans can't enforce shit on gods.
The guy can also move to different country that legally allow harem and be the king since one of the girl is a princess. He live happily, then die having lots of children and grandchildren cry for him.
Or John can win and he joins ember to take over the world because they "understand" him. Resulting, with a timeskip, in John becoming a supervillain tyrant and arlo+serphina+high tiers have to team up for one final battle