Keres by Pepper North

When all hope has evaporated, his search will focus on replacing himself.

Rimi has existed in the haze of a mountain shielded by clouds. Always dreaming of the sun, she’s never risked basking in its warmth. As the last hope for desperate dragons, being cherished as a fated mate is not this female’s destiny.
Keres has lived without a mate for too long. His battle to cling to sanity is coming to an end. Only one choice remains—abandon his need for a Wyvern mate to hunt something more elusive. The clock is ticking as blackness consumes his mind and soul.
Change has come to Wyvern. A centuries-old pact between the founders and their powerful allies could save the inhabitants of the city once again, but only a dragon Daddy can truly guard his mate from harm.