They say relationship chemistry cannot be predicted. Cupid, the ancient Roman god of love, is portrayed as a “putto” — an Italian word meaning a chubby male child. Why is Cupid a putto, and not a wise old man? Perhaps because (as any mother of a young toddler can tell you) kids that age can be irrational and mischievous. And so, Cupid is portrayed as irrational and mischievous — ready to wreck havoc in love.

That makes some sense because emotions, which are a primary driver in relationships, cannot be predicted by any law of science we know of. We use terms like “odd couple” or “opposites attract” to describe the apparent unpredictability of love. But just because something can’t be entirely described by science, doesn’t mean science has nothing to say about it.

This is where attachment theory comes in. It is a branch of psychology that originally studied how children get along with their parents. The “Strange Situation” test developed by Mary Ainsworth is a famous example of attachment theory in practice.

More recently, attachment theory has been applied to dating and relationships. Dr. Amir Levine, a professor of Clinical Psychiatry at Columbia University, is a pioneer in this field. He speculates that relationship success can be predicted by the attachment styles of a couple. People fall into three categories: Secure, Anxious or Avoidant attachment styles. Dr. Levine claims that in dating, it is common for men to be Avoidant (the “commitment-phobes”) and women to be Anxious (the clingy types). Based on his clinical research, he warns that although Avoidants and Anxious types are drawn to each other, this combination of attachment styles is incompatible.

In attachment theory, securely-attached partners (the “Secures”) are the ideal. They are loving, confident and reassuring. They can communicate effectively and diffuse conflicts easily. According to Dr Levine, because Secures are so good in relationships, they are rarely single. Once hitched, they stay hitched. So dating pools tend to have high concentrations of Anxious and Avoidant types. The Secures are still there, but it takes patience and luck to find them.

My fiancé is a Secure. He is warm, loving and reassuring. I can’t give credit for meeting him to Dr. Levine (it goes to God), but his theory of attachment styles helped me understand the type of person who I could be in a healthy relationship with.

Often, the whole responsibility for a successful relationship is placed on women, who are expected to know how to deal with emotionally-stunted partners (even abusive men). Women who express needs are sometimes told they are too clingy, and taught that their needs are not valid. This is another reason why I like Dr. Levine’s theory: He does not blame women (or men) for a relationship failing. Instead, he relies on clinical research to make predictions about relationship success that can be applied by anyone.

Relationships are not a science, but neither are they astrology.