MTL - Villain Rescue System - Chapter 21 first world 21

As a precocious child, Lycoris suffers from a strange sense of deja vu. On the day her father told her about her fiancé, she realizes that her fiancé was a character from an otome game she once played in a previous life.

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

She was forced by her husband and his mistress to jump into the sea and commit suicide, only to be rescued and taken care of by the jerk's uncle for seven years.

This is actually the story of a teenager who, after the devastating and spartan-like training of his crazy cool/Gong teammate, turned into a super amazing point guard that could blow up the skies even though he may seem low-key on the surface.

Also, Nie Chuan is Reese’s first love.

Nie Chuan: I’ve decided to promote you to becoming my best friend!

Reese: If I can be your best friend, it just means that you have no friends.

Nie Chuan: Hey! How could you say that! Do you know what it means to be my best friend?!

Reese: I’m sleeping.

Nie Chuan: It means that when I get married, my bride may not necessarily be her, but my groomsman must be…

Reese: The groom must be me.

Nie Chuan: What– you want to snatch my bride away?! You’re too inhumane!

Reese: Sleep.

- Description from Novelupdates