This is because women being sentimental by nature are bound to feel more hurt if a relationship does not work out and especially if she does not know why the relationship never worked out. Relationship is all about communication and understanding the partner.
Having said this there are many things that most women instinctively do that immediately turn off the men. If small things like these piles up on men everyday till they decide enough is enough and this lead to failure of a relationship. It is obvious that no true relationship can break due to the fault of the women alone but there are certain things that women must know to be in any successful relationship.
A woman must learn to stick to the boundaries that they have mutually set for each other. It is almost always observed that it is the women who try to negotiate the boundaries that they have mutually agreed upon. Men most of the times take this as being treated in an unfair manner. Some women like to keep their feelings to themselves. They never open up unless they are prompted to. This is by nature of women however this leads to a feeling of isolation and frustration in the minds of men. Women most often try to change guys to the perfect man of their dreams. This is a fatal mistake. Even though they understand men they may not accept their habits and rather try to change them or refuse to accommodate them.
Most men would look to this as being selfish and some even are hurt even though they do not express it most of the times. Women tend to compare men to other men. This is something which all men hate when it is done unfavorably. It only works if the guy is compared to his idol and no one else. Many women also expect a lot of desired actions that most explicitly turn the man into a lady. This is certainly not encouraged by any man all over the world. To make a relationship work a woman must keep these factors in mind and remember that only with understanding can breakups be avoided.