Ascribing to the theory that Yussa is a golden dragon... dragons are obviously solitary creatures, and there are so few of them around. It could make sense for there to be some equivalent to a mating season for them- maybe every few centuries older dragons get the urge to seek each other out, reproduce, and then go back to blissfully ignoring each other.

Unfortunately, Yussa’s kind of busy. Between managing a district of mortals and exploring exciting new magical pursuits, he doesn’t have the free time to fly around the continent looking for a mate. So, he decides to ride the symptoms out on his own. Which works fine, until another dragon starts getting spotted edging closer and closer to the city, and Yussa knows the only way he can get rid of them is by giving them what they came for.

Bonus points!
+a pair doesn’t need to be male/female to mate, either because of weird dragon gender dynamics or reproduction being more a magic thing than a biology thing, or any other reason
++Wenforth being aware of what’s happening and doing his best to accommodate Yussa
+++Yussa struggling to sit through, like, city council meetings and other mundane thzings early on
++++oviposition/egg-preg