The research is very clear that compatibility is based much more upon how individuals are similar than upon how they are different. Similarities of communication and conflict resolution styles, personality, interests, coping styles, and so on, are predictive of long term satisfaction in relationships.
Intuitively, wouldn't the old expression, "Opposites attract," add to the "chemistry," or excitement in a relationship? Wouldn't two people who are different in important ways be able to complement one another and make the relationship more powerful?
My response to this argument is that even couples who are highly similar in ways that add to the long term happiness in their relationship are still quite different in many important ways. Each person in a dyad comes from different genetic material and has a different learning history, since they grew up in different families.
Couples who are highly compatible, based upon their similarities, are still capable of spending a lifetime discovering and appreciating their differences. They can also find many ways to use their differences to strengthen their ability to function as financial, social, and parenting partners.
How do similarities strengthen a relationship?
The most powerful predictor of long term compatibility in our research is how couples communicate and resolve conflict. Why is this important?
Conflict is inevitable in any long term relationship. It cannot be avoided. If it is avoided, the couple puts their relationship at grave risk of eventually dying on the vine.
Conflict in relationships arises when couples differ regarding something that is important to one or both of them. When couples are able to find a way to communicate their preferences to one another in such a way that the other person "gets it," they are more able to empathize and compromise. When this occurs, they put their relationship on a healthy growth projective, rather than a downward spiral.
Couples are most able to effectively communicate when they have similar communication and conflict resolution styles. Thus, some couples are quite direct and assertive in how they communicate, some are very indirect and intuitive with one anther, and others use a combination of direct and indirect ways of communicating.
How do other similarities, such as personality, interests, coping styles, sexual and romantic styles, financial styles and family values add to compatibility? These different areas add to the overall intimacy of the relationship by contributing to something the couple is able to share together. Maximizing similarities in these areas also provides less of a basis for conflict. Each of these areas also contributes uniquely to the relationship in ways that will be more fully explored later.