type
noun
pronounced
/open-relationship/
emerged
recent
status
mainstream

open relationship

   neutral, modern

the one-line answer

A relationship where both partners consent to romantic or sexual connections with others.

An open relationship is one where both people have agreed that exclusivity is not required. The key word is both. And agreed.

mainstream

Your coworker might use this word.

01 / in the wild

hear it move.

description
they're in an open relationship. seems to work for them.
They have a mutually agreed arrangement allowing outside romantic connections.