Admittedly, I have never been in a relationship before (*unsurprised gasps*). However, that doesn't mean I am not interested in them. More specifically, I'm interested in learning about different types of relationships. The ones I know most about are closed monogamous and polyamorous relationships.
What are types of relationships do you know of, either from personal experience or from reading/seeing/hearing about? I'm curious about how many forms of them there really are out there.