The supporting character's harem is very normal - Chapter 37 Miam!

In a distant future, the empires of mankind span the galaxy, and glorious Earth has devolved into a peripheral backwater.

In Shanjing city in the Asian region, Wang Zheng’s dreams of becoming a mech pilot are crushed when his college entrance exam genetic score turns out a pathetic twenty eight, barely above an animal.

To make things worse, people get the impression he attempted suicide after being rejected by the campus beauty.

Then the closest thing to a family he has, the old man in the book store across the road, goes missing, leaving him only a mysterious birthday present.

This novel is also known as Master Fu's Mysterious Darling Wife

She is the The Young Miss of Military family Shen, her face is peerless, her temperament is cold, and she is her family’s treasure, but isn’t accepted as one’s child by her mother;

He is The Sole Heir to the top giant Fu Family, his power is unparalleled, indifferent high-born, the captain of the mysterious military force, and the youngest commander-in-chief.

Because of her grandmother’s wishes, she married him at lightning speed. She thought that it was a marriage that she needed, but she didn’t expect to be greeted with his extreme pampering.

- Description from Novelupdates

This world is not reality, nor am I the protagonist.