Complex sentence: Within a year of both men moving to Melrose Avenue, the superficial relationship between Nilsen and Gallichan began to strain: both men slept in separate beds, and both began to bring home casual sexual partners.
Split into simpler sentences: Within a year of moving to Melrose Avenue, the superficial relationship between Nilsen and Gallichan began to strain. They slept in separate beds, and both began to bring home casual sexual partners.