A Therapist Tells Us What Makes Two People Click In A Relationship

Romantic chemistry is part art and part science. Here is what new science has to say on the topic.

By Jourdan Travers, LCSW | September 5, 2022

Many people come to therapy asking questions about their intimate relationships. Some common questions are:

  • "How do I know if he/she is the one for me?"
  • "How do I know if I'm looking for the right qualities in a romantic partner?"
  • "What do I do if I'm having doubts about my relationship?"
  • "How can I make him/her love me more?"

Psychologists will first tell you that romantic attraction is a nuanced and unpredictable part of life. There are no guarantees or magic bullets. It's impossible to make someone love you or for you to make yourself love someone else.

There's a magical and random element to love and romance that insulates it from our best efforts to grasp it fully.

With that said, research in the field of romantic attraction and close relationships has identified some important factors that tend to ignite the spark of love and keep the flame lit. Here are three things that have been scientifically shown to make two people click.

#1. Birds of a marginally different feather flock together

One thing relationship scientists can say with some certainty (although, when it comes to human behavior, there are exceptions to every rule) is that opposites do not attract. There is a point at which two people's personalities, values, preferences, and interests are simply too divergent to make for a sustainable relationship. Physical attraction alone is generally not enough to keep the wheels of romance turning.

On the other hand, there is such a thing as two people being too similar. This is a less common occurrence in the world of relationships, but it is sometimes observed by couples' therapists.

The sweet spot, it seems, is when two people have a solid bedrock of similarity — say, for instance, they share similar values and have overlapping interests — but they differ in ways that spice up, or complement, the relationship. This could mean that one partner is more extroverted than the other, or that one partner has a more analytical mind while the other has a creative mind. In other words, they bring something to the table that their partner doesn't.

Of course, these are scientific generalizations and they don't necessarily apply in every case. Some partnerships defy all the rules of what should make for a good relationship and yet they work in their own peculiar way. Sometimes, when you ask someone to explain their seemingly illogical partnership, they say, "I don't know, it just works." The best explanation for love is sometimes no explanation.

#2. Commitment is paramount

It is difficult to maintain a healthy romantic relationship without a strong undercurrent of trust and commitment. You probably don't need science to tell you this, but it does anyway.

One study published in the Proceedings of the National Academy of Sciences analyzed data from over 11,000 romantic couples and found that relationship commitment — or, more specifically, the belief that the relationship would last forever — was the most important factor in predicting the overall quality of the relationship.

An equally noteworthy finding from this study was how difficult it was for the scientists to predict whether or not a relationship was a happy one from the trove of data they had at their fingertips. To be precise, people's answers to things like relationship trust, appreciation, sexual frequency, conflict, and communication didn't do a whole lot better than a coin flip in predicting whether a couple deemed themselves to be in a desirable relationship. Love is still largely indecipherable from the prying eyes of science.

#3. The importance of physical and sexual chemistry cannot be overlooked

Anyone who tells you that sex is unimportant to the long-term health of a romantic relationship isn't necessarily lying, but they are probably uninformed. The same study also found sexual satisfaction to be the third most important factor in predicting relationship satisfaction across the 11,000+ couples included in the analysis.


It's unlikely that science will ever fully crack the code of love. But that doesn't mean its insights can't help guide you to a better future for you and your relationship. When evaluating your romantic partnerships, keep an eye out for:

  1. Enough similarities but also a few key differences
  2. Someone who understands commitment
  3. A physical spark