Under the Yum Yum Tree (1963)

Hogan owns and operates the Centaur Apartment complex. He rents the units to young women only at less than half their market value in order to spy on them lasciviously and seduce them. After Hogan's latest conquest, college professor Dr. Irene Wilson, moves out when their romance goes sour, Hogan is more than happy to rent that apartment to blonde college student Robin Austin, and even happier when he learns that she will have a slightly-taller brunette roommate. What Hogan doesn't initially know is that Robin is Irene's student and niece, and that Robin's roommate will be her boyfriend, fellow college student David Manning. Not wanting to mistake lust for love, Robin convinced a sexually-frustrated David, with whom she hasn't yet slept, to this platonic cohabitation arrangement just to see if they are truly compatible as people before they decide to get married. When Hogan finds out about David and the arrangement, he tries subversively to thwart any romance between Robin and David, all the while trying to get Robin for himself. Once Irene finds out about Robin and David's arrangement, she tries first to ensure that they stick to it and second that Hogan isn't trying any funny business with Robin, all in the name of protecting her niece. Irene, a professor of Education for Marriage, might be able to add some professional wisdom and firsthand knowledge of Hogan to keep the process moving.