Composite seal and coupling

A seal and coupling, wherein the seal has a thin profile including a primary sealing element that provides both a face and radial seal, and a secondary or backup sealing element that provides a face seal. The secondary or backup sealing element seals against leakage past or through the primary sealing element, and the retainer may be made of a fluid impervious material for blocking permeation of fluid from the primary to the secondary seal. The retainer may also function to prevent over-compression of the sealing elements, while also maintaining a radial spacing between the sealing elements.