What are your thoughts on open relationships?

Personally, I would never do one, and would be offended if anyone ever offered. To me, I think that if I were in a relationship with someone and they wanted to do this, I would be hurt. “What, am I not enough for you?” It is like a license to cheat. But, I don’t think less of anyone for being in one.

What do you think about them?
Would you ever partake in one?
Have you?

The entomology of this question:

In the gay world, it seems to be an unwritten rule that guys assume it is o.k to have an open relationship. Well, none of my CLOSE friends feel that way, but I know a lot of guys that do. To me that is asinine! Am I a prude for thinking that I would never do that?