The gemara at the end of Ta'anis tells us that the two biggest yamim tovim for Klal Yisrael were 15 Av and Yom Kippur. On those days the girls would go out into the fields and dance and the boys would come and find their shidduch (simple solution to the shidduch crisis). The girls who had money would say, "Marry us for our money," the girls who had yichus would say, "Marry for yichus!" and the girls who had nothing would say, "Marry l'shem shamayim and then afterwards give us gold jewelry."
We all know why Yom Kippur is a special day, and the gemara gives a hosts of reasons why 15 Av was a special day, among them that on that day the dor ha'midbar stopped dying for the sin of cheit ha'meraglim. But why were these days in particular the days set aside to make shidduchim? What does finding a girl to marry have to do with the nature of these days?
Secondly, what does the gemara mean when it tells us that the girls who said to get married added, "And buy us gold jewelry!" It seems incongruous with the call to act "l'shem shamayim." Were the girls who said that being disingenuous and just needed a way to snatch a boy when they had nothing else going for them? Do we really have to be that cynical? It's strange that the gemara even bothers add this line about gold when it has nothing to do with the shidduch itself. Maharasha writes that it's just a "milsa b'alma," but maybe there is more to it.
There were two major sins that Klal Yisrael committed en route to Eretz Yisrael: 1) the sin of the cheit ha'eigel = abandoning G-d; 2) the sin of the meraglim = abandoning Eretz Yisrael. There was one group of people, however, who did not involve themselves in either sin -- the women of Klal Yisrael. By the cheit ha'eigel the women did not willingly turn over their gold jewelry to their husbands to make the golden calf. When it came time to apportion Eretz Yisrael, it was the Bnos Tzelafchad who demonstrated their love of the land and demanded a portion.
Yom Kippur is the tikun of the cheit ha'eigel. On that day Hashem gave us the second luchos, a second chance after the first were broken by Moshe in response to the eigel.
T"u b'Av is the day the dying of the generation of the midbar stopped. It brought closure to the cheit ha'meraglim.
For the women who needed no tikun, these days are "feminist" holidays -- days when they could boast of their superiority. Not holidays of modern feminism, where women want to be men, but Torah feminism, when women can be proud of their own stellar achievements. On these days the women reach out to their male counterparts and call, "bachur, sa na einecha," lift up your eyes and look at the madreiga we reached! These are days of shidduchim because on these days the bachurim reach out to find partners to help bring up their level of ruchniyus.
The conclusion, "Adorn us in gold jewelry," is not just an aside, but is part of the whole message, explains the Sefas Emes in Likutim. The women could boast that they deserved to be adorned with the gold that they did not turn over to the eigel, the gold that we men so eagerly surrendered for avodah zarah.
When we lost Eretz Yisrael and the Mikdash and went into galus, we lost T"u b'Av. We lost the tikun for the cheit ha'meraglim. All that is left is Yom Kippur, the tikun for the cheit of avodah zarah.
Maybe a reinvigoration of T"u b'Av is something to look forward to as we get closer to geulah.