This is the second article in a four-part series about your relationship with work: Part 1 | Part 2 | Part 3 | Part 4

Continuing with our series on the relationship we have with our jobs, this week we will take a look at knowing when it is time to move on. (For more on interviewing once you have made the decision to leave, check out Part I of our series.)

Relationships can end in many ways and for many reasons. In this case, it is almost always a good idea to try to remain friends afterward, as awkward as that may be. As we have said, it is a small world, there is no reason to burn bridges if you do not have to. And, it is still common practice to do reference checks, so why give your ex a reason to badmouth you?

The important area on which to focus your energy is understanding the reasons to break up with your employer. The most common boil down to three categories: the deal breaker, the slow death and the greener grass.

1. Deal breaker

Simply put, you have lines the employer should not cross. Such lines could be universal, like a hostile work environment, harassment or other regulated areas. (These are also often the reason not to remain friends, but it can still get tricky to talk about such matters to a potential new employer.)

But the lines can become subjective quite quickly. For example, many people would agree that after being overlooked for a promotion, it may be time to go. What people might not agree on is how many times they would have to be overlooked before they left. One might be understandable, three could be a problem.

Know what your personal deal breakers are and be ready to commit to looking elsewhere if that line is crossed, lest you fall into the slow death category.

2. Slow death

This is probably the most common and the most difficult to identify. Usually, this is paired with some external factor that helps you realize you are on your way to racking up a thousand paper cuts. It could be a friend's new job relationship helps you realize how bad yours has been, or you have experienced some significant life event that has helped you refocus your priorities.

Either way, this reason often happens is you have not clearly defined your own deal breakers. Things happen. As isolated incidents, they are a problem but you move on. It is only when you look back and tally the issues that you realize this relationship is not working for you.

Start looking around at other relationships — it could be true that the grass is greener.

3. Greener grass

Which leads us to the third common reason for a breakup. In recent years, people were taking what they could get, either because of the economy or because they did not realize they really did have options. Either way, many employees are currently underemployed; the relationship is working great for the employer but you are pretty much being taken advantage of.

Start by checking out what people doing similar jobs in similar companies are making, the benefits they receive and the hours they work. Is it close? Or are you toiling away and racking up vacation days for 10 percent less?

As in the other cases above, take a minute to assess your relationship. Be honest with yourself. if it is not working for you, it might be time to call it quits.