Here's something that interests me: things that are somewhat or very similar to the nonmonogamous practices we recognize and discuss here but that exist mostly or completely outside of the typical poly/ENM discourse.

For example, least in major US metro areas it's quite common for people to date more than one person at a time. It's often referred as multi-dating. While most of these people don't see themselves as polyamorous or nonmonogamous, many of them are actually not dating with the goal of settling down in a monogamous partner but rather to enjoy the fun and variety of seeing multiple people casually.

Another thing I've come across is defining your relationship status as single-ish or mostly single. This describes a situation where you date one or more people and can have a variety of connections with different mixes of sexual and nonsexual interactions, but you are quite independent, not exclusive with anyone and you don't call anyone boyfriend or girlfriend. I've recently been chatting with someone who describes herself like this, and based on what she's told me, we'd probably classify her relationship style as solo poly while she had never even heard of the term.

What other nonmonogamy-adjacent or nonmonogamy-related things have you encountered?