Keltess
Keltess is the dragon equivalent of "puberty" and can begin as early as 90 years old, or as late as 180 years old. However, most dragons begin their Keltess around the age of 120 and complete it by the age of 150. Once a dragon has completed Keltess, regardless at what age this occurs, they are considered by all dragons to be an adult, and are treated as such. Since the age at which Keltess begins and ends varies from dragon to dragon, there is no official "age of adulthood" within dragon society, and thus its completion must be determined by a council of dragons who decide if an eligible youngling has completed the requirements of Keltess, and reached full physical and sexual maturity.
If that is confirmed, then the individual is no longer considered a youngling, but instead has become a full fledged adult, after which they begin receiving all of the benefits and privileges that come with that status. This includes the right to date, to marry, have children, etc. Any dragon who has not completed their keltess is forbidden from dating, or having literally ANY intimate relations with the opposite sex. Those are considered adult privileges, and younglings are strictly forbidden from partaking in them on risk of severe punishment. If an elder dragon, or even a fellow youngling, are found to have broken these rules, heavy, severe punishment is almost always meted out to the offender. In some cases, depending on the offense, this has included death.
Yes, the dragons take keltess, and the protection of younglings before keltess, and while they are going through it, very, very seriously. It is protected, and revered, with nearly the same severity and importance as the marriage covenant that two dragons swear between one another when they become joined with each other. So, in the same way that the marriage bond in dragon society cannot be broken, save upon the death of one of their spouse, the boundaries and restrictions of keltess carry the same, or sometimes even a greater, weight of assurance with all dragons that the boundaries be maintained, no matter what is required to achieve that.