Last of the Red Hot Lovers(1972)

Successful seafood restaurant owner Barney Cashman is having a mid-life crisis and is bored with his marriage. When he learns that his mother is not at home one day each week, he decides that he will use her apartment to have a series of romantic flings. But Barney turns out to be inept at the art of the extra-marital affair. He gets some women to come to the apartment, but they won't sleep with him.