Complex sentence: Loras and his squire, Olyvar, have sex, and unbeknownst to Loras, Olyvar is a spy for Lord Baelish and reports to him the Tyrells' plan to marry off Sansa.
Split into simpler sentences: Loras and his squire, Olyvar, have sex. Unbeknownst to Loras, Olyvar is a spy for Lord Baelish and reports to him the Tyrells' plan to marry off Sansa.