What is a "successful relationship?"

[Whit]

      I was just reading over UT's 'Emotionally Distant' thread in home base when I got to thinking about the phrase, "successful relationship." What the hell is that?
      To me a relationship is successful when everyone involved comes out of it better than they went into it. By this standard I've had several successful relationships. However, society seems to place importance on the continuation of the relationship. Even calling long term harmful relationships successful as long as the parties involved choose to stick together. At the same time, people that come together make each other better and stronger are said to have failed when they go their separate ways.
      Why is this? Also, is it correct?

      By the by, I realize that this is pretty insensitive in light of what UT is going through. Still, I believe that it's a valid point of discussion and that UT won't be offended as it falls right into the development through discussion that he seems to have created the site for. I hope I'm right about that UT, no offense meant.