You're Bored

The most common reason that men break up is that they get bored.  In fact, it's probably the most common reason that anyone breaks up with anyone.  And it's a good reason too.  If you're disinterested in the relationship, the odds are good that neither party is getting their money’s worth.  The problem with this is that a lot of people get bored only because they get lazy.

The trick to avoiding boredom is constantly refreshing your memory of what you're in the relationship for.  It helps if you're with someone who reminds you why you like them just by being, but if you're still not getting it, just try putting in a little more effort.  We all get comfortable once the initial phase is over.  We know her favourite foods.  We've become experts on what gets her off and we begin to slip into routine.  This isn't the way it has to be though.  Just making the attempt to keep the romance alive is enough.  Go on dates—real dates.  Most couples don't do that after they get through their beginning phases and it leads to decline.

You've Checked Out

A lot of guys stay in a relationship long after they realize that they don't want to commit themselves to it just for the sake of laziness and routine.  But if you know that the person you're with isn't the one that you want to spend your life with, you should get out of there, more for their sake than your own.  It's not fair to exist as a half-hearted member of a couple.  It's sneaky, underhanded and selfish.

Sexual Incompatibility

Depending on how important sex is to you and what kind of sex is important to you, this can be a crucial issue.  A lot of people can suffer through some less than satisfactory sexual chemistry for the sake of a great personal relationship, but most people aren't that altruistic.  Sex is too much a part of the modern dating world for it to do anything but influence your feelings for someone.

If you find that your rhythms don't match up and it's something that you can't correct, then it might not be the right relationship for you.  That said, you can try to fix things.  A lot of times, the best sex comes out of work and a process of education.  You'll never have better sex than you will after taking the time and effort to actually learn your partner's body and their preferences and educating them about yours.

Man Up

Breaking up is just as important as asking someone out on a date, but more difficult.  It's uncomfortable, it’s taxing and it’s unpleasant, but it has to be done.  The most important thing to remember is that you can't let fear of confrontation keep you from it because it's just prolonging the inevitable.