Starting this Tuesday, June 29th (the 17th of Tammuz in the Hebrew calendar), a three-week period begins, lasting until the 9th of Av (July 19th and 20th this year), called Bein haMetzarim, literally "between the boundaries." What do these two days consist of, and what happens between them?
Our sages decreed fasts on both days, for different reasons. However, the common denominator of both dates is the destruction of the Temple in Jerusalem, the first and second time. Furthermore, because of the close connection between these two dates, they decreed that we should refrain from certain joyful activities, such as weddings, getting our hair cut, wearing new clothes, and listening to or playing music.
So, what is the purpose of these restrictions? One way to look at it is that we simply behave in accordance with the times: since this is a time of mourning, we behave in a manner of mourning. Apparently, we should behave this way all year round, because the Temple remains destroyed throughout the year (and indeed, there are constant expressions of this idea, as the psalmist says, "unless I had set Jerusalem above my joy," from which our sages learn that even in joy one must remember the destruction of the Temple). However, at times directly related to the suffering of the Jewish people, we fast and behave in a manner of mourning.
From a deeper perspective, it is not just a ritual, a way of behaving, like living in accordance with the times, but it is a way of making ourselves aware, through our actions, that we can and must reverse the situation.
Our sages explain the reasons why the Temples were destroyed: first, because people despised the Torah, and second, because of unfounded hatred among Jews. The fact that the Temple remains destroyed is clear proof that we have not yet corrected the cause of its destruction. Therefore, we must act in the opposite way to these causes, that is, emphasize appreciation for the Torah and unfounded love for all Jews.
The fasts and mourning practices during this time of "Bein haMetzarim" awaken us from the vanity of daily life and focus on correcting the past to create a different future. In other words, throughout the year one should conduct oneself with appreciation and respect for the Torah and with unconditional love for all Jews, Ahavat Yisrael, but we become distracted and lose our way, immersed in the day-to-day. Bein haMetzarim is a time for pause and refocusing.
That is why it is customary to increase in the study of Torah these days and to increase in Tzedakah - charity, in accordance with the verse of Ishaia (1:27) "Zion will be redeemed with justice, and her captives with Tzedakah.".
May our refocusing in these days fulfill the verse "Out of oppression I call to you, O God, answer me in the vastness," that is, may we succeed in calling upon God in these days of oppression (limits and oppression in Hebrew are similar words, metzarim and metzar) and be answered with true Divine vastness, with the coming of our righteous Messiah, swift in our days.