On this daf, we find reasons why the fifteenth of Av is a Yom Tov.
Although we feel somewhat consoled from after midday on the tenth of Av—it is from then that the laws of mourning cease—our recovery reaches its peak on the fifteenth of Av. On the ninth of Av, we have finally faced our faults and we prepare to change them. We work to slowly transform negative attitudes and actions. This is similar to one who must get into shape for a great event. To do one’s best, it is imperative to isolate weaknesses and work on them. This is one reason why the ninth of Av is a moed and the fifteenth of Av is a Yom Tov. Although this is the avodah of these days before Elul, we can do this throughout the year (Chochmah Umussar)