Complex sentence: He is a fan of Lord of the Rings, and is currently in a relationship with Dr. Carrie Allen, unbeknownst to Davis, however, is a mole working for Jack Harper.
Split into simpler sentences: He is a fan of Lord of the Rings, and is currently in a relationship with Dr. Carrie Allen. Unbeknownst to Davis, however, she is a mole working for Jack Harper.