Compersion

Compersion or Compersivity is the feeling of joy one feels when witnessing another person's joy, such as in witnessing a toddler's joy and feeling joy in response, the feeling of joy associated with seeing a loved one love another. It is contrasted with jealousy.

This term is often used by polyamorous relationships or by polyamorous individuals, often in contrast to the many monogamous individuals who experience jealousy when their partners fall in love with another. Many polyamorous individuals experience compersion with seeing their partners fall in love with another.

History
It is unknown when the term was coined, however it has been around since 2010.

Flag
The flag was coined by Tumblr user beyond-mogai-pride-flags on August 31st of 2019. It has no confirmed meaning.

Resources

 * https://beyond-mogai-pride-flags.tumblr.com/post/187401377910/compersive-pride-flag
 * https://www.psychologytoday.com/us/blog/the-polyamorists-next-door/201312/jealousy-and-compersion-multiple-partners-1
 * https://www.urbandictionary.com/define.php?term=Compersion
 * https://www.huffpost.com/entry/compersion-a-polyamorous-principle-that-can-strengthen-any-relationship_b_6803868