Surviving marriage in yandere world

Rei just wanted to read novels in peace, no girlfriends, no drama, no accidental death by divine lightning meant for a cockroachBut for now, he is the son of a powerful duke, reincarnated into a fantasy world full of magic, monstersand dangerously obsessed women.They were childhood friends of that duke son. They all are sweet noble girls. One is emperor's daughter and one is my older sister. Now they're grown up and they all want one thing.And that thing is Rei.Welcome to a world where love means stalking, loyalty means stabbing your rivals, and marriage proposals come with blood pacts and fireballs and even my system mocks me. Rei fiances battle each other daily and his life is a romantic comedy except it's also a warzone.Oh, and his final mission is marry the Demon Queen. A literal succubus overlord trying to conquer the world.Somebody please help him. In a realm of swords, sorcery, and yandere chaos. So, he can find peace or at least keep his limbs attached.