I Just Want to Freeload on Your Luck - Chapter 9

Xiao Yu, who was a student from modern Earth, accidentally transports to another world and becomes the lord of a territory. Facing an unfavorable situation, he vows to take back his family business, build his new territory, kill all of those who covet his wealth, and dominate the world!

- Description from Novelupdates

When necromancers perform a great ritual to summon an undead servant, they bring a powerful vampire into their world. And now, their fate is sealed as food, but for Klaus, this is just the beginning of his adventure. In a cruel world where people will do anything for power and immortality, he is already very strong and immortal, so what's left if not start a family and have fun stepping on arrogant people through the way?

As childhood sweethearts, they were made to engage under the manipulations of their families. It involved having to to live in the same room and sleep together.

One night, she is accidentally made drunk, and in his delirium, he kisses her only to realize he enjoys it. From time to time, he would sneak a kiss on her, but his “crime” is eventually discovered in an accident. After being accused by her, he says with a smile, “You are my wife, why can’t I kiss you?”

The two people’s daily routine is full of bickering and mutual discrediting of each other.

Although he claims to disparage, he actually cares intensely about her. He feels crazily jealous when she is close to other men, to the point of tying her to his side, so that she becomes exclusively his.

- Description from web

In her former life, she was robbed of her status, her looks, and her reputation.