Da** he is so cute 
well I have a small spoiler
well I have a small spoiler
Spoiler!
Actually according to the novel the dragon Duke is the only ML for Calypso since he is her soulmate. And in the side stories she gets two more husbands. And the Dragon Duke binds himself to her as soulmate when she saves him from the attack of panther clan. Also the dragon duke is very obsessive of Calypso that he is willing to do anything just for her. Even if it hinders his own growth and basically grants her all her wishes.
I like to post spoilers for the stories I find interesting because I don't have much time to read novel due to busy schedule you will find me in most romantic historical manhwa comment sections
Thank you!