Are You ok With Your Spouse Having a "Platonic Relationship" With Their Ex?

Once you're married or in a committed relationship, what are the rules of engagement, for how you interact with your ex-lover, or ex-sex partner? Is it an insecurity, that people don't want their spouse to be friends with their ex's? Is it possible to have a pure platonic with someone that you've been sexual intimate with? Are you oppossed to your spouse having a friendship with their spouse? Can you be completely platonic with someone, after being sexually intimate? There will also be guest, speaking about their experiences with platonic relationships. "Darryel's Daily Dialogue...where positive words, manifest positive actions."