Complex sentence: Leonard overhears the Koothrappalis talking about Priya moving back to India the following month and then storms in to confront her and also happens to reveal that they are in a relationship.
Split into simpler sentences: Leonard overhears the Koothrappalis talking about Priya moving back to India the following month. When he storms back in to the room to confront her, he reveals to her parents that they are in a relationship.