This is the fourth book in Owen's Fire Edge series. I don't see this as a stand alone although for the romance it is but if you don't read the previous books you're missing rich world building. There is a crossover series Inferno Rising which this book in particular begins to weave threads for what looks to be an exciting conclusion.

The Protector tells the story of Lyndi a rare female born dragon and Levi. Levi has recognized her from the moment he met her centuries ago as his, Lyndi has fought the attraction because as a female born dragon she can't have children and doesn't Levi to settle for less than she thinks he could have, not realizing he has known that she is all he needs since he met her.

This is a very sweet (with a lot of heat ) story of their journey toward a happy ever after.