Spoiler alert!! he ends up with one of them and no karma to the other 2.
The better ending would be the MC will commit a svicide in front of those 3 like jumping off a cliff near the sea and the 3 of them will thought that he died and will live with regrets and have nightmares everyday that they killed the MC.
On the other hand, the MC was found floating in the sea and some good people help him but he lost his memory, everything in the past. So he will basically live as a brand new man in the island with good people cuz he deserves it. If mc will not die then at least torture the 3 of them. Death would be a joke since they deserve worst than that!
I've read someone's comments about the ending in the novel and oh gawd, I hope the author would take a U-turn from that.