If maintaining a happy and fulfilling relationship were easy then 40%–50% of all first marriages, and 60% of second marriages, wouldn’t end in divorce. Moreover, divorce is not an inevitable outcome from an unhappy marriage. The percentages of those that say they are “unhappy” in their relationship are even higher. Unmarried couples, not having the same social and legal constraints, walk away from long-term relationships at even higher rates than those that are married.

When the question of why relationships fail is asked, the reasons often pointed to include external pressures such as financial problems, children and parenting styles, work pressures and other time commitments; and interpersonal reasons like a lack of trust or respect, sexual differences, differences in expectations, addictions, and a nearly endless list of other reasons.

Each of these, however, is less a reason for failure than they are a source of conflict. Studies show that how constructively, or poorly, individuals in a relationship respond to and manage conflict has a far greater Influence on the success or failure of the relationship, than the specific source of the conflict. Whether financial pressure or infidelity, the behaviors that are exhibited during conflict tend to point to a greater or lesser likelihood of working through a problem successfully.

Humans are genetically programed to seek relationships. In ancient times as now, relationships were important for both survival and our psychological well-being. But the complexities of modern life have added countless stresses and additional sources of conflict that our ancient ancestors could not have imagined. As a result, conflict in modern relationships, both in frequency and intensity, has increased.

In addition to the detrimental impact on the sustainability of today’s relationships, these added stresses have also had an impact on our overall health. Conflict in relationships has been linked to the onset of depressive symptoms, eating disorders, binge drinking and alcoholism. Although married individuals are healthier on average than unmarried couples, marital conflict is associated with poorer health and with specific illnesses such as cancer, cardiac disease, and chronic pain. One theory holds that these health issues are due to alterations in immunological, endocrine, and cardiovascular functioning that occurs as a result of conflict and hostile behaviors.

Regardless of the source of conflict, individuals fall into patterns of behavior that tend either to support a positive resolution, or hinder it. These behaviors include words or other communicating signals such as tone, facial expressions and body movements. Couples locked into negative exchanges, even when trying to resolve the conflict, may use phrases like, “You’re not listening to me,” in an attempt to improve the situation, but deliver these words with expressions of sadness or irritation. Despite the intention, these negative signals can elicit a negative response from the partner – continuing a downward cycle of negative behaviors.

Successful conflict resolution occurs more often when individuals use and apply more positive or affirming words, tones and expressions. For example, a spouse that responds to “Wait, you’re not letting me finish” with a genuine, “Sorry . . . please finish what you were saying,” are more likely to start a pattern of positive behaviors that lift the couple to a positive resolution.

The behaviors we exhibit are largely controlled by our thoughts and feelings about what’s happening. Those thoughts influence our interactions during conflict. For example, when an individual interprets a partner’s behavior (e.g., coming home late from work) in a way that promotes conflict (e.g., “he only thinks about himself and his needs”), rather than in less confrontational ways (e.g., “he was probably caught in traffic”), the result is a greater likelihood to display negative behaviors such as annoyance and anger. Negative expressions increase the likelihood of a negative response and so begin that conflict cycle again.

Couples that are in successful relationships must contend with the same financial issues, problems with children, work related pressures, and all of the many other hardships and sources of conflict that befall unsuccessful couples. Decades of research suggest that the key difference in a successful relationship is the frequency and consistency of supportive behaviors such as active listening, compassion, patience and acceptance that take place during the conflict. Couples that think in more positive assumptive terms (assuming the best) and who behave in more positive and encouraging ways (using positive words and expressions) during the conflict, tend to have more successful conflict resolution, and happier and more sustainable relationships.

If all of this was easy, most relationships would work. There are so many factors that influence our thinking and thus behavior – how we were raised, culture and societal influences, personality and temperament, prior experiences, even physiological and psychological considerations– that changing “negative behaviors” is sometimes nearly impossible without help.

Relationships tend to begin well. Over time, experiences and circumstances can change a relationship in ways that affect happiness and contentment. It is helpful therefore to pay attention to the changes as they occur, and to recognize when sources of conflict are beginning to take their toll, and to seek help – discover new ways to think and communicate – that can get you back to the happiness you experienced when it all began.