While I do not like cheating by any means,
I do think a lot of choices were made by this guy in haste to get to this point which make me feel that the better option would have to be the warrior girl.
A princess who doesn't really love the MC and a King using him as an heir,
honestly he shouldn't have married the princess back then and just moved away with warrior girl before the country turned them into political pawns.
I think moving forward they should just either "disappear" or fake their deaths somehow and move on from their previous life.