Sinful Obsession (1999)

Zanthe is a bored housewife who has a sexually unfulfilling marriage to a successful lawyer, Alan. She also has sexual fantasies about her husband's coworker McCabe, and when she finds out that his beautiful dates are actually high class prostitutes, it piques her interest. She secretly begins working at the high class brothel that McCabe frequents, and gets into a mutually obsessive relationship with a creepy regular customer, Morgan. The stress of her relationships and secret double life cause her fantasies to border on hallucinations, and may put her in even greater danger.