The High Holidays are a time of introspection and self-assessment in anticipation of repentance, forgiveness, thanksgiving and rejoicing. It is a season of healing.
Tu BiShvat, called the "New Year of the Trees," falls at a seemingly incongruous time of year.
Tu BiShvat is a minor festival whose provenance dates only to the time of the Second Temple. However, the kabbalists who clustered around the great fifteenth-century mystic Isaac Luria of Safed placed great weight on the holiday, creating new festivities, gatherings at which hymns were sung, fruit (particularly carob) was eaten, and four cups of wine were taken (as in the Passover seder).
Although Jewish weddings may take place on the days in between the Jewish High Holidays, it is generally discouraged because during that period, also known as the Days of Awe, we are focused on the solemn themes of the season.
Here is the quintessential Jewish question: How do we emulate God? We are told that we were created by God. We are told that we have a divine spark within us.
"Tu" (the Hebrew abbreviation of 15th) in the month of Shvat was set (Hillel's opinion generally overrules Shammai's) as the beginning of the tithable year for tree fruit: Calculating the tithe on fruit starts again for fruit that sets after that date.