Broken Heat by Wendy Rathbone

When Elon no longer experiences heats, Omega Island is his last reprieve.

Omega Island is a private tropical island in the Caribbean specializing in sexual healing techniques for omegas who cannot be helped by traditional therapies.
Three years ago, omega Elon lost his mate. At 30, he’s still young enough to have a family. But there’s a huge problem, when his mate died, his heats vanished. No heat doctors seem able to help until one prescribes him a nice retreat: a week of healing at Omega Island.
Mykel is an alpha sexual surrogate who specializes in omega sexuality. A patient who cannot experience a heat is the perfect challenge for him. There are many natural ways to induce heats and he wants to try them all—if his patient is willing.