Anyone can help me find the title of a book or the author?

it was about a king who hunt dragon that was deemed as an evil being becaue they like to kidnapped maiden, but he got bitten then he slowly starts transforming into one.
He then met a widow whose husband also turned into a dragon. He was very attracted to this widowand later fall in love with her
Later on he completed his transformation and he run away scared. His council then hunt him. His brother seek his woman and ask for help. She quickly found him in a cave before the council arrived. Later they had s*x and found out the reason dragon kidnapped maiden is because they want to find their mate. And he turned back to human after that and he can still hear his dragon speak to him. When the council arrive he already turned back into human so all is well

it has 4 books. The second - fourth book is about their children finding their own mate
it was post long ago, I believe below 2015

thank you!