.. copy-and-pasted from... https://www.chabad.org/library/article_cdo/aid/2263474/jewish/Tammuz.htm .. an article written by Alex Levin..

Sunrise in Jerusalem - By Alex Levin Sunrise in Jerusalem - By Alex Levin Tammuz (Tamuz) is the fourth of the 12 months of the Jewish calendar, counting from Nisan. The month of Tammuz begins the “season” of the summer. The three months of this season are Tammuz, Av and Elul. The 17th day of Tammuz—a fast day that commemorates the day when the walls of Jerusalem were breached by the Romans (in 69 C.E.)—marks the beginning of a period known as “the Three Weeks.” This is an annual mourning period, when we mourn the destruction of the Holy Temple and the cause of our current ongoing exile. It reaches its climax and concludes with the fast of the Ninth of Av, the date when both Holy Temples were set aflame (423 BCE and 69 C.E., respectively). Because of this and numerous other tragedies that occurred throughout Jewish history during this period, we lessen the extent of our rejoicing during the three-week period leading up to it. See: Tisha B'Av and the Three Weeks Why the excessive mourning for more than 2,000 years? G‑d is our Father, and we are His children. And during galut (exile), we constitute a dysfunctional family. We have been expelled from our Father’s home, and our relationship is strained. This is certainly not the way the relationship should be—and this wasn’t always the case. There was a time when we were coddled by our Father’s embrace. His love for us manifested itself in many forms, including miracles, prophets, abundant blessings, and a land flowing with milk and honey. At the center of our relationship was the Holy Temple, G‑d’s home, where He literally dwelt among His people and where His presence was tangible. All the suffering that has been our lot since the day the Temple was destroyed is a result of our exiled state. This is why we mourn the destruction of the Temples. We believe with perfect faith and pray that the day is near when we will be returned to our Father’s home and once again feel His love. We look forward to a brighter future, when the world will finally reach the culmination of its purpose, and be infused with everlasting peace and goodness.