Enemies to lovers

leads are on opposite sides of a war

ML is a demon trying to destroy the FL's clan

FL has sworn vengeance on the ML's family

Leads are from opposite warring clans

FL goes back in time to take the ML's power and kill him

FL is a human, ML is a demon out to harm humans. 

ML is an idol, FL is the "anti-fan" whose mission is to expose his bad personality to the world

Leads are divorced, the FL joins the ML's company to get her revenge and take him down while he hires her for the same reason

The leads both consistently try to trick and hurt each other

the leads start out as allies but something happens that turns the FL against the ML, it becomes her mission to take him down

the leads' royal families are enemies

ML and FL are from warring kingdoms, ML is plotting to murder the FL at the beginning

ML is the FL's military enemy and captures her

FL enters ML's household because she thinks he killed her family so she wants revenge

FL is the daughter of a murderer who killed the ML's parent

leads are enemies forced into marriage

leads are political enemies

Leads run afoul of each other in college and the ML does his best to hurt the FL

FL has a revenge plot against the ML's family

FL wants revenge against ML (though she doesn't remember it), ML hates FL

leads had a non-amicable divorce

FL thinks the ML is responsible for her father's death. ML thinks the FL is a spy come to kill him (he's technically right)

star-crossed lovers

FL hates ML and makes it her mission to expose his secret

leads are on opposite sides of a war of gods & demons

ML kills FL's family, FL wants to kill ML

ML bullies FL, FL betrays ML

ML bullies FL

ML hates women, FL hates men

Though the leads are married, they are both trying to get the other killed

ML poses as the son of FL's enemy

FL and ML's families are feuding

ML and FL's family are enemies

I won't say too much for spoiler sakes but the leads are from opposing clans basically

ML is seeking revenge against FL for the death of his fiance