Griffin Drake by Emilia Hartley

Griffin Drake always gets left behind. While his cousins leave Grove to have adventures, he’s stuck babysitting his increasingly distant and crazy cousin, Jasper, the king of the mountain. When his cousins come home to help, they all find mates, one after another. Griffin is left alone, without even a way to meet a mate. He’s always been bad at talking to women.
Then he meets Lilah, who is down on her luck and easy to talk to. He offers her a job as his pretend girlfriend, so he won’t have to live through another family get-together as the only un-paired dragon.
Suddenly, he’s not behind at all. Lilah moves in, gets along with his family, and lights up his life. He was sure the universe had forgotten about a mate for him, but now he knows Lilah is the one. All he has to do is convince her it’s not all make-believe.