I found yet another very interesting parallel between Luke 17 and Tu B'Av. First, we have the reference to people being given in marriage and as previously noted, Tu B'Av is the day of the year most common for Jewish weddings, where there is alot of eating and drinking.

Luke 17:27 People were eating, drinking, marrying and being given in marriage up to the day Noah entered the ark. Then the flood came and destroyed them all. 

Here we have another interesting parallel with the PLANTING reference:

Luke 17:28 It was the same in the days of Lot. People were eating and drinking, buying and selling, planting and building. 29 But the day Lot left Sodom, fire and sulfur rained down from heaven and destroyed them all. 30 It will be just like this on the day the Son of Man is revealed.

Tu B'Av marked the end of the year for planting.

Tu B'Av was instituted (in the Second Temple period) to mark the beginning of the grape harvest, which ended on Yom Kippur. It was also the time when planting of trees and crops was to end for the year.

The last day for planting was on Tu B'Av. Jesus said that up until the day that Lot left (symbolizing the purhearts leaving the world at the time of the Rapture right before the Sudden Destruction), people were planting. These verses are talking about the Rapture because it mentions Noah entering the ark for protection and some being taken, while others are left behind:

Luke 17:34 I tell you, on that night two people will be in one bed; one will be taken and the other left. ³⁵ Two women will be grinding grain together; one will be taken and the other left.”

The Lord certainly seems to have left alot of "clues" behind pointing to this date in His Word!