It’s possible I just haven’t played a large enough number of MMOs, but I’m relatively certain that there are no games which pop up a helpful notice telling you to stop playing the game forever at a certain point. That being said, I know that I personally have signs indicating I should probably stop playing. If I find myself dreading logging in, for example. If I no longer can answer the question of why I’m playing. If I lose all of my RP partners and see it as a relief rather than a loss. If certain individuals are associated with the game. You get the idea.
As much as we might say that certain things lead us to leave the game, I think most of us have a more organic system; it’s not one thing that causes us to drop WildStar or Star Wars: The Old Republic or Guild Wars 2 from our play rotation, it’s a lot of things that we tie back to one observation. But perhaps that’s just me. Tell me, dear readers: When do you know it’s time to stop playing an MMO? Do you ever regret making the decision when you do?