Swimfan

Swimfan, also known as Fanatica, is a 2002 American teen psychological thriller film directed by John Polson and written by Charles Bohl and Phillip Schneider. The film stars Jesse Bradford, Erika Christensen, and Shiri Appleby.

Ben shares some of his past with Madison he began doing drugs five years ago, which led to crime and six months in juvenile hall, which saved him because he ultimately realized his passion and talent for swimming. Although Ben tries to end the date, Madison convinces him to go to the pool. Her aggressive flirtation lures Ben in, and despite his initial hesitancy, the two end up having sex. However, both agree to remain friends and agree not to discuss their steamy encounter with anyone.The next night, Ben goes to a party at Amys house. Amy introduces Ben to her new friend, who turns out to be Madison. The two pretend to have not met one another yet. Shortly after, Madison begins to obsess over Benshe stops by his house to meet his mom and bombards Ben with emails and instant messages. Ben realizes her unhealthy behavior and furiously demands that she leave him alone. Bens lying begins to eat at him, and he decides he will confess his infidelity to Amy, but Madison tells Amy first. Madison begins dating Bens rival teammate, Josh. Right before their biggest swim competition, Ben is disqualified for having steroids in his urine. Ben is outraged and suspects that Madison had convinced Josh to set him up. Ben confronts Josh about the drug test, revealing his suspicion. Days later, Madison accidentally calls Josh by Bens name while they are kissing in a car. Josh realizes that Madisons obsession with Ben is real, and tells her off. ........

Source: Wikipedia