Complex sentence: He became close friends with Dan, and the two were frequently seen paired on the beat together until Dan resigned, since then he has been paired with PC Roger Valentine, PC Benjamin Gayle and PC Tony Stamp among others.
Split into simpler sentences: He became close friends with Dan, and the two were frequently seen paired on the beat together until Dan resigned. Since then he has been paired with PC Roger Valentine, PC Benjamin Gayle and PC Tony Stamp among others.