Pool Days (1993)

Justin, a 17-year old entering his final year of high school, gets a job as a life guard at a fitness center. Surrounded by hard bodies of both sexes and instructed by his boss to keep an eye on the steam room to report any men having sex, Justin begins to divine the direction his erotic feelings point. In separate incidents, Vicky and Russell, two older co-workers, hit on him. He tries out responses to both, and then must figure out what to do with his new self-knowledge.