Shavua Tov. The last Mishna in מסכת תענית says in the name רבן שמעון בן גמליאל that there were never such happy days in Israel as טו באב and Yom Kippur.
Tu B’Av was a day designated for Shidduchim, and Yom Kippur was the day of forgiveness to Hashem. Rav Shlomo Mann זצ”ל explained this most surprising statement. Tu B’Av was the time when one found their soulmate. According to the ארי ז״ל, one fulfills ואהבת לרעך כמוך, loving your neighbor as yourself, when one loves his spouse as himself. Therefore, the fifteenth of Av represents the ultimate in closeness between בין אדם לחבירו, between man and man.
Yom Kippur represents the ultimate bond, connection, and love, between man and G-d, בין אדם למקום. When we are elevated with sincere prayer and feel Hashem close to us, we are brought to a feeling of contentment and tranquility.
Rabban Shimon Ben Gamliel could easily have been referring to these two special days in the Jewish calendar, when we achieve love of man and love of G-d at the highest level.