Have you ever had a casual or open relationship with someone?

To be honest, I have never had an open relationship nor would I ever. I never understood the need for having an open relationship. To me, a relationship is between two people. Introducing other people makes it seem more like friends with benefits to me. However, that's just how I view things. I know an awful lot of people who have open relationships and it works well for them. They don't want a true commitment, so it helps. If it works for them, then I'm happy for them, but I think I would die if I had to be in an open relationship.