What kind of an avodah can there be for bein adam lachaveiro?
When we think about yamim tovim, we think about specific actions that we do in order to celebrate or mourn or repent. They tend to have specific rules and strictures and tend to be regulated. They have their own liturgy.THey are about specific action, not about a “feel-good” attitude.
On Tisha Be’Av we have the chamisha inuyim and Megillas Eicha. On Sukkos we have the sukkah, arba minim, leining, etc. On Purim we have the mitzvos of the day, one of which is the closest I can think of to an avodah on a yom tov that is based on bein adam lachaveiro, mishloach manos.
What would the avodah for the day be, going around to x number of people like at Kiddush Levana and saying shalom aleichem with no prejudice in our hearts? Having an asifa in Citifield? Doing a chessed? Those aren’t specific avodahs- two of those are things that we should be doing anyway (veahavta lareiacha kamocha) and one of those was simply a good thing to do.
I do know that there is (obviously) a lot of buzz about ahavas chinam around this time of year, and I think that that’s the best kind of avodah you can have in bein adam lachaveiro for Tisha Be’av, as long as people follow through.
In the meantime though, the point really is the mourning for the loss.
(A tangential point- considering that the first beis hamikdash was destroyed because of the transgressions of the 3 mitzvos yehareig ve’al yaavor, maybe the avodah of the day should be that every person should focus on not killing his neighbor, or on not being Hindu for the day.)