At this point I don't think Makoto has any romantic feelings left for his wife he's fully smitten by Michi. After all those years of being neglected I understand how reasonable it is to fell out of love, at the end of the day it was impossible to reignite your love just because your partner suddenly showed effort/changes.
So I guess the best option for those two is divorce. Guys don't get married if you only see your partner as a convenience (the mistake this couple did).