As much as I'd like it if Karma and her netori co-conspirator to go out long term, i find it hard to believe such things are on the table.
If Karma cannot feel shame, is she similarly unable to feel proper love, or is it only negative emotions that are affected?
If she can't feel any affection toward the guy, I wouldn't want her to have to enter a relationship she doesn't want.
If, on the other hand, living the happy life which Moon wanted, with the man Moon loves, while also depriving Moon of that Happy reality, fits into Karma's unique brand of vengeance; I'm all for it!
They do say the best revenge is a life well lived, after all.
Wishful thinking, I know. The best we can realistically hope for is that Karma repaid the guy's cooperation with fantastically mind-blowing "ramen", following which they amicably go their separate ways.