I've always understood polyamory to be the practice of maintaining multiple loving relationships at once, whereas polyfidelity is the subset of polyamory in which the relationships form a closed system.

As I mentioned to karenbynight, I seem to identify as polyfi because, while I'm not in a strictly "closed" relationship, it's awfully rare for me to get involved with someone past smooching at a club, etc.

It is a source of much frustration to me that people tend to use polyamory when what they are actually participating in is polyfuckery. But that's humans for you.

SRSLY. Damn those humans and their opposable thumbs.