MTL - Traveling Through Ancient Times To Be a Shopkeeper - Chapter 13 marriage

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

Immediately after Gu Changge realized he had transgressed into a fantasy world, the world’s protagonist, and fortune’s chosen, vowed to take revenge on him. Envied by all, he not only has the female lead head over heels for him but he’s also treated as a distinguished guest wherever he goes. Fortunately, Gu Changge’s prestige and power are superior to everyone else’s, so shouldn’t it be easy to trample on a mere fortune’s chosen?

Four years after the Third Nightmare, something unexpected happens. A group of people find themselves in a strange theatre, which tells them to react to someone's story...?

“Who would have thought that one ordinary review could instantly fuck your life? Definitely not me”******Luke was your average teenage boy—with an unhealthy obsession for light novels.After finishing a new read titled “The Hero’s Obsessed Harem,” he jumped online to post a review. His biggest issue? The so-called “hero” kept stealing other men’s love interests, and somehow, the story praised him for it.Right after posting the review, he got an odd reply from the author:“You think my book is flawed? I’ll make you regret that.”Luke brushed it off as a salty writer who couldn’t handle criticism—until everything went dark.The next time he opened his eyes, he was in the body of Riven Von Grave, the fourth son of the low-ranking Grave baron family—an irrelevant extra in The Hero’s Obsessed Harem. Riven was a forgotten character, engaged to three duke’s daughters since childhood, only for all three to abandon him for the so-called hero. And to make matters worse, he was fated to die in a war against demons—utterly forgotten.But Luke isn’t having any of it.Screw fate.Screw the plot.And most of all, screw the author who threw him into this mess.Armed with a mysterious system and pure spite, Riven is going to rewrite his destiny, and win back his fiancées as well.But with every change Riven makes, he changes the story, and pulls a calamity bigger than the demons toward them. What will he do when he realizes the impending doom, will he be able to fix his own mistakes?