Bianca (1984)

Michele, a young mathematics professor, moves into a new flat. Lonely, depressed, and neurotic, he spends his time obsessively monitoring the lives of the couples around him, especially his neighbors, a young pair struggling to make their relationship work. When Bianca, a new teacher at the local high school, enters his life, Michele finds himself falling in love. At the same time, a string of murders rocks the neighborhood, casting suspicion on him.