The Villain Is A Perfect Fit For The Role - Chapter 100

Knowing she married a wrong guy, what would she do to deal with the subsequent marriage lives?

In order to pay for her brother’s medical expenses, she had to replace her own sister to marry the rich family's elder son . She always thought she was married to the elder one, but she did not know her husband was nominally the younger son He Yi Ning.

He Yi Ning, the real heir of the rich family, the ruthless business emperor, the ruthless workplace tyrant, and her sister’s dreaming husband. When she found out that the person who married her was He Yi Ning, she stunned and asked, “Shouldn’t i be your sister-in-law?” He smiled charmingly: “Are you unhappy with your husband?”

The Empress who dies in torture, An Rushuang is her name. After she wakes up, she finds herself has time-travelled to when she was twelve years old, but she would turn into Major General’s white horse at night. He is a general who orders about the winds and clouds on the battlefield, and she is a little girl lives in her boudoir seclusively.
She endeavors to change her fate, and he spared no effort to win every battle. They meet each other every day, well, it’s night to be accurate. Is that a dream or not? She pleads to marry the seignior to win peace for her family, only to find he is the one she is going to marry.
“Growing old with you under the same roof is my long-cherished wish”, thought them both.

- Description from Novelupdates

Shiao Yi is an 18 years old boy from a war-torn future, he is badly injured while escaping his enemies and wakes up in a strange, old-fashioned world with no technology—only magic, swords, and monsters.He’s saved by a kind but mysterious knight named Dominic and taken to a stone fortress where people think he’s just a lost child.As he heals and tries to hide who he really is, Shiao Yi slowly realizes he may have ended up in another world.With no idea how he got there or if he can ever return, he must learn to survive, understand magic, and figure out if this strange new place could be his chance to live a real life—for the first time ever.

My childhood friend went to the academy.