polyversary 

The yearly reoccurrence of the date on which, two or more people in an open relationship, celebrate their love. It could be the annual commemoration of an open marriage but does not have to include a committment ceremony, It may be celebrated by any form of non-monogamous relationship that involves multiple people. It could be a celebration of the first date, the first kiss, or the day they became official on Facebook. It may be celebrated by couples, triads, quads, or any number of other poly configurations.

I'm frustrated that his polyversary with his girlfriend is not legitimized by society the way that a legal marriage would be.

or
This month marks my seven-year polyversary with James and Sharmila, our triad became official at the pride festival when we made polyamory signs and marched in the parade.

or
My polversary with Michael is easy to remember because it always falls on Valentines.

polyversary by Blisscoach June 30, 2023

Palversary 

Pets in the same household that sometimes start as adversaries but slowly become pals, some of the time, but can flip back to adversaries any moment. The pet version of frenimy.

Our older cat has begrudgingly accepted the kitten as a worthy palversary.

Palversary by YellekG June 14, 2019