A Woman in Flames(1983)

Original title: Die flambierte Frau

Eva, an upper-class housewife, frustratedly leaves her arrogant husband and decides to enter the call girl business. She lets Yvonne, a prostitute, teach her the basics and both set out for prey together, until Eva starts an affair with Chris, who turns out to be a call boy, as well. Consequently, she moves into his penthouse, large enough for both to offer their services separately.