Cruel Intentions 3 (2004)

Cassidy Merteuil, the distant cousin of Kathryn Merteuil, arrives in Santa Barbara, California to attend college. There she meets Jason Argyle, a former friend from her high school also attending the school. Jason gets a roommate, Patrick Bales. Jason and Patrick form a mean-spirited partnership of seducing and dumping various young women on campus. When both of their latest conquests bore them, Jason bets Patrick if they can seduce a particular newcomer, who is under the wing of Cassidy. But nothing is what it seems as a triangle of Cassidy, Jason, and Patrick forms with each one scheming to outwit the other.