Are there any where the other guy in a love triangle is the male lead's best friend? He knows that the male lead loves the female lead and then intentionally tries to steal her away. Maybe he succeeds at first and makes her fall for him, but in the end she realizes her love for the male lead.

Boys Over flowers

Autumn in my Heart

Time between dog and wolf

Iris

Full House

Princess Man

My girl - the 2nd lead did not try to separate them, he just tried to woe the girl

Lovers in Paris - does it count if they are brothers?

Chichago Typewriter

Jealousy Incarnate

You're beautiful

Cunning single lady