like sea55star, I would also wonder what isn't being said -- often that is infinitely more important than what is said. However, I do know that even the best relationships can fall on hard, stressful times and make you feel like you just want it to end. Sometimes it's hard to differentiate what exactly it is that you want to end -- the hard times, or the relationship? Often the relationship isn't at fault for the stress, but it is all that you can control. Start with thinking back to when you first got together, and remembering what attracted you to your significant other in the first place. As cheesy as it sounds, remember the good times -- try even writing a story (try a hub if you like) about the best time you had together. That done, do something special for your significant other, just out of the blue, to show them how much you care. Next, go do something for yourself, by yourself, that helps alleviate stress -- maybe it's going for a jog, seeing a movie with your best friend, or heading out to that wine tasting.
Once all that is done, ask yourself if you still feel like leaving. If so, try to identify why. Next, sit down with your significant other and discuss your feelings with them, including why you think you have those feelings. You may be surprised to find out that what has caused your issues has also caused problems or changes with your significant other, and you may both be more than willing to work out a solution.