There is a huge variety of non-monogamous relationships, and of people in them. Others start off as officially non-monogamous. Most polyamorous relationships include promises which, while not necessarily lifelong, set out boundaries for the relationship. Not all poly relationships involve bisexuality or even homosexuality. E.g. one woman may have two husbands who are not sexual with each other.
Polyamorous relationships can take different shapes.
Where three people are each faithful to the other two, that could be called a polyfidelitous triangle. Many people find it hard to imagine that someone can have more than one partner without jealousy becoming a problem. Sometimes people can't imagine how it could work, and they imagine that poly people must have a miserable time. Copyright Jennifer Moore 1996. If you're not charging money for it, you don't have to pay me any.