Usually couples break up when there is some kind of tension or friction between the two people. Sometimes there is a serious source of difference that makes living together impossible, perhaps a conflict of values or interests or actions and habits. When people come together, these differences are usually not pronounced or simply irrelevant due to the newness and excitement. But with time, these differences show themselves and they begin to take their toll.
Some issues can be worked out from the get go, however, if you are made aware of them, and more importantly, if you let your partner know what they are. One simple example would be cleanliness. Suppose your partner is a very messy person and from the moment that you step into their apartment, you notice an offensive wreckage, clothes strewn everywhere, a filthy kitchen, toenail clippings left on the countertops, everything in wild disarray. In the beginning, you might not say anything at all, or you might drop small hints, but that cleanliness issue will not seem to you like a reason to break up ever. It will seem like something that might work itself out with time and turn into something that is not an issue.
However, as the years pass, it will become an issue, particularly if you are a clean and organized person. The sloppiness of the other will grate on your nerves and make you irate, and you will find yourself trying to reform that person and change their behavior. Of course, people cannot easily change their behavior and so you will begin to feel resentful and helpless and angry and it will become disruptive.
Perhaps, if you had made it clear in the beginning, you might have been able to work through it sooner or realize things that would perhaps prevent a messy break up after years of time and energy investment. Basically, communicating about dislikes and displeasures is an essential way of making change happen, and doing it from the start is important, because if you wait a long time and hope that things will change, usually they do not. And if you work on it from the start, you will be able to see if it is a hopeless case much earlier and not have to prolong the relationship if it just won't last.
Another way to prevent a break up is to take a break when things get bad. This might sound like a break up, but actually, it is a way to clear your head and mind and get some space when things get really bad. Sometimes, in a relationship, a couple can reach a point when things just seem irreversibly bad, and instead of breaking up, taking a break can help you two gain some perspective and get some distance from all of the issues at hand. This can help you see what is important and to balance that person with all of the issues to see what holds greater importance. Also you will be able to see what life is like without that person and to see if it is something that is worth the pain of separation.