I remember the evening my wife broke the bad news to me. The conversation had been spinning out of control -- I just hadn't seen it. I desperately wanted things to be different. I wanted to believe that what I was experiencing wasn't true 

And then she said those six words that changed everything:

"He's just not that into you."

I had never thought about it that way. I thought he had been there for me for more than 8 years! Suddenly, it was crystal clear that the man I had called a mentor was no longer on my team. To be clear, this was not a business coach I was paying -- but someone who had been teaching me for several years. It was hard to take -- he was a mentor first, and a boss, and (I thought) a friend.

Looking back, it shouldn't have been a surprise. There were some warning signs that I just didn't want to see. Here are five things to look for, if you think it might be time to let go of a mentor.

They miss meetings. I call a "mentor" someone who has experience that can help you get to your next goal. I should be meeting them at least once a quarter. If they reschedule more than two meetings, be wary.

They hold back. A mentor by definition has more experience, and therefore a bigger network. They should be getting you to think of new people to build relationships with. If they withhold making introductions, be skeptical.

They don't ask new questions. Sure, I seek out experts in their field to learn from what they already know, but over time I expect that they'll ask me a new question from time to time. If you always talk about the same things with a mentor and they always tell you the same stories, maybe it's time to move on.

They discourage expansion. This is what happened to me. When I started talking about the books I wanted to write in 2000, my "mentor" at the time actually encouraged me NOT to pursue that goal. I should have been warned.

They don't acknowledge progress. As a mentee, it's your responsibility to share status updates with mentors from time to time. If, over a year or so, you don't get some form of acknowledgement, be warned. 

But you might be thinking: How can you fire a mentor? Yes, it's ok to do. However, this isn't something they taught you in school. You have to take your vision, your work ethic, your opportunities and your challenges to someone who is willing to stand by you.

By letting go of the kind of mentor who brings you down, you open up to an entire new set of possibilities.