What does The Mating Bond represent?

The mating bond represents the true love that exists between some faeries, including between Rhysand and Fayre, though Rhysand knows about this bond long before Fayre. This bond is separate from the bond that exists between them as part of a bargain struck in the first novel of the series. At the end of the novel, the King of Hybern breaks the bargain bond, though not the mating bond.