Love and breakups are part of an existential cycle that nobody can live without, even though they manifest in different levels and under a variety of unpredictable scenarios.
The emotional suffering and joys that such experiences bring can't be erased from memory, so it's important to confront them and analyze personal believes wisely. Such exercise requires the understanding of the purpose of love and its positive outcomes. And, even though it may be interpreted differently by each person, it can be conceptualized and redefined according to experience.
The most common approach to love is the need to share a life together with another person, which allows us to label those we meet as willing or unwilling, while being aware of who we attract and reject. This said, relationships fail when the path shared diverges into more than one single direction. However, the one being rejected knows that he or she has failed in providing something necessary for the two paths to become unified. As an example, a woman that criticizes men, makes them feel rejected and unloved, decreasing their compassion towards her. And, this happens because there's a contradiction between sharing a common purpose while holding to divergent believes.
The problem with breakups and divorces is that nobody wants to confront the problem and tell the other what went wrong, but he or she, will naturally need to make his own assumptions and conclusions, in order to find peace in his or her mind. Affairs are the most common assumptions, but even this can be justified by an unhealthy relationship, either they exist or not.
There are unknown rules in love, which lead to all kinds of difficulties related to maintaining a healthy relationship, but, if known, could allow maximizing the success of existing ones as well.