What's the story/history/reason behind calling the 15th of the month Av 'Chag Ha'Ahava' ?
And why, and how was or is this 'Chag Ha'Ahava' celebrated?
Extracted from here
There were seven joyous events that happened on the 15th of Av
- The dancing maidens of Jerusalem
Said Rabbi Shimon ben Gamliel: There were no greater festivals for Israel than the 15th of Av and Yom Kippur.On these days the daughters of Jerusalem would go out... and dance in the vineyards. And what would they say? "Young man, raise your eyes and see which you select for yourself..." (Talmud, Taanit 26b)
- The dying of the generation of the Exodus ceased.
After the incident of the spies, G‑d decreed that that entire generation would die out in the desert, and that their children would enter the land in their stead (as recounted in Numbers 13 and 14). After 40 years of wandering through the wilderness, the dying finally ended, and a new generation of Jews stood ready to enter the Holy Land. It was the 15th of Av of the year 2487 from creation (1274 BCE).
- The tribes of Israel were permitted to intermarry.
In order to ensure the orderly division of the Holy Land between the twelve tribes of Israel, restrictions had been placed on marriages between members of two different tribes. This ordinance was binding on the generation that conquered and settled the Holy Land; when the restriction was lifted, on the 15th of Av, the event was considered a cause for celebration and festivity.
- The tribe of Benjamin was permitted to re-enter the community.
On this date the tribe of Benjamin, which had been excommunicated for its behavior in the incident of the “Concubine at Giv’ah,” was readmitted into the community of Israel (as related in Judges 19–21).
- Hoshea ben Elah opened the roads to Jerusalem.
Upon the division of the Holy Land into two kingdoms following the death of King Solomon, Jeroboam ben Nebat, ruler of the breakaway northern kingdom of Israel, set up roadblocks to prevent his citizens from making the thrice-yearly pilgrimage to the Holy Temple in Jerusalem, capital of the southern kingdom of Judah. These were finally removed more than 200 years later by Hoshea ben Elah, the last king of the northern kingdom, on Av 15, 3187 (574 BCE).
- The dead of Betar were allowed to be buried.
The fortress of Betar was the last holdout of the Bar Kochba rebellion. When Betar fell, on Av 9, 3893 (133 CE), Bar Kochba and many thousands of Jews were killed; the Romans massacred the survivors of the battle with great cruelty, and would not even allow the Jews to bury their dead. When the dead of Betar were finally brought to burial on Av 15, 3908 (148 CE), an additional blessing (“Hatov Vehameitiv”) was added to the Grace After Meals in commemoration.
- “The day of the breaking of the ax.”
When the Holy Temple stood in Jerusalem, the annual cutting of firewood for the altar was concluded on the 15th of Av. The event was celebrated with feasting and rejoicing (as is the custom upon the conclusion of a holy endeavor), and included a ceremonial breaking of the axes, which gave the day its name.
Because of numbers 1, 3 and 4 above, the article here says that
Tu B’Av is a great day for weddings, commitment ceremonies, renewal of vows, or proposing. It is a day for enhancing current relationships or defining anew what you are looking for in a partner. It is a day for romance, explored through singing, dancing, giving flowers, and studying. The rabbis teach that on Tu B’Av one begins to set more time for studying as the High Holidays approach.
Wikipedia notes that
“In modern-day Israel, it is celebrated as a holiday of love (Hebrew: חג האהבה, Hag HaAhava) etc.