Written by Horav Yosef Yeshaya Braun, member of the Badatz of Crown Heights
It’s forbidden for ex-spouses to interact with each other socially. However, there’s a mitzvah of machzir gerushaso (remarrying one’s divorced spouse) – unless he is a kohen or she had been married to another man in the interim.
Contemplating a remarriage would obviously necessitate the former spouses to meet. In this case, contact should be made in a tznius’dige (modest) fashion, and both parties should be aware of the meeting’s purpose.
They may not meet in a private setting due to the issur of yichud (forbidden seclusion), nor should they meet in public so as not to give the wrong impression to people who may recognize them.
They should rather choose a venue where those present know why they are meeting or where there are only strangers around.
If they reconnect in a proper manner, they are actually performing a great mitzvah.