The fact that he apparently has ties to some dragon hunting kingdom makes absolutely no sense. If they knew anything about dragons in this setting, I'm fairly certain they wouldn't be antagonizing the embodiment of the strongest dragon that only the previous hero, the grandfather of this mf, could defeat. Their kingdom would probably just say "fuck that" and let the noble get killed to not have to deal with the world's strongest dragon over literal nonsense, but the author wanted a harem, so let's make the dragon experts into dragon idiots and make the "devoted husband" go off to woo a woman with a fiance while his wife watches.