What Is Chemistry In A Relationship? Definition, Signs, And Insights

Medically reviewed by Julie Dodson, MA, LCSW and Dr. April Brewer, DBH, LPC
Updated November 18, 2024by BetterHelp Editorial Team

Many people in love talk about having a spark or an indescribable, magnetic-like pull towards their partner. This electric feeling is often referred to as chemistry. But what is chemistry exactly? Read on to learn about relationship chemistry, including what it is, signs of chemistry, and how to build more of it in your relationship.  

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What is chemistry in a relationship? 

Chemistry in a relationship is the intense feelings of excitement, attraction, and emotional connection between people that draws them together. Chemistry can be felt in any relationship, but it can play a crucial part in romantic relationships. Research has defined interpersonal chemistry as “a perceived instant connection that exists when meeting a person for the first time.”

Chemistry can be obvious and intense in the beginning, or it may develop over time as the relationship progresses. Chemistry can change forms as a relationship progresses. For example, the initial chemistry you experience with your partner may be mostly physical attraction that causes you to feel nervous or your heart to race. However, after the honeymoon phase has subsided, you might find that you still have chemistry, but it’s more about safety, shared interest, and connection. 

Types of chemistry 

There are several types of chemistry one can experience, including: 

  • Friendship chemistry – Friendship chemistry is when you’re drawn to another person on an emotional, friendly, or intellectual level. It’s a connection based on mutual respect but doesn’t usually involve sexual or romantic feelings. 
  • Physical chemistry (sexual chemistry) – Physical chemistry is what someone has for a person with whom they want to be intimate. You may feel sweaty, short of breath, or warm when talking or looking at someone towards whom you experience sexual chemistry. 
  • Romantic chemistry – Sexual attraction and chemistry are typically a part of romantic chemistry, but not always. Romantic chemistry centers around romance and the desire to have a romantic relationship with someone.

The science of romantic chemistry 

Romantic chemistry isn’t a recognized scientific term. However, it’s an experience that has been studied. In the initial phases of connection and attraction, the human body experiences an array of chemical changes. Estrogen, testosterone, cortisol, dopamine, and norepinephrine all rise, and serotonin decreases. These changes often make a person feel excited, slightly obsessive, and anxious. 

As relationships progress, serotonin and cortisol levels return to normal, and vasopressin and oxytocin begin to rise, causing romantic partners to feel more attached. These chemical changes and interactions throughout the phases of love may explain what causes the physical sensations involved with chemistry. 

However, chemistry is often more than a physical experience. It’s also usually an emotional connection of some kind. This connection may be shared interests, similar senses of humor, easy conversation, or compatible life goals. While chemistry can be the physical spark of attraction, it can also be a deep connection that leads to trust and communication in a healthy relationship. 

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10 signs of chemistry 

Chemistry can be difficult to define, so it may be hard to know when you’re experiencing it. Here are several common signs of strong chemistry. 

  • Body language – When people have strong chemistry, you can usually see it in their body language. They may lean towards each other, mirror each other’s movements, or find ways to touch. Their body language toward each other will likely be open and welcoming. 
  • Eye contact – Prolonged or frequent eye contact can be a sign of attraction and chemistry. If two people make repetitive eye contact or look deeply into each other’s eyes, it could be a sign of chemistry. 
  • Nervous energy – In the early phases, chemistry can elicit nervous energy. You may feel butterflies in your stomach, have a racing heart rate, or experience sweaty palms when you’re around someone with whom you have chemistry. 
  • Compatibility – Shared interests, goals, and humor can all indicate a strong level of chemistry. However, compatibility alone doesn’t usually create chemistry. You may be compatible with someone on paper but still not feel a desire to be physically or romantically involved with them. In this case, the connection may be more well-suited for friendship. 
  • Physical attraction – While not the case for everyone, for many people, physical attraction and a desire to be intimate with them is one of the strongest indications of early chemistry with another person.
  • Emotional connection – Chemistry can also create a strong emotional bond between people. They may feel a sense of empathy and understanding toward each other, even if they’ve only known one another for a short period. This early emotional connection can lead to feelings of affection and love down the line. 
  • Flirting – If two people find themselves flirting, it could be a sign that chemistry exists between them. Playful banter, compliments, facial expressions, seductive lines, and other types of flirting between two people may indicate chemistry. 
  • Easy conversation – Chemistry can make it easier to have effortless or deep conversations. People with chemistry may find themselves talking for hours and not even noticing. 
  • Time flies – People with chemistry may notice that time flies when they’re together. Hours can feel like minutes. 
  • Physical touch – When people have chemistry, they often find ways to touch. For example, you may touch their arm while laughing or graze their hand while talking. You’re also usually hyper-aware of when they touch you. 

These 10 signs are all indications of chemistry in the early phases of connections. As a relationship evolves, many of these signs will still exist, but the nervousness will often be replaced with comfort. As a couple grows closer, the warmth they feel for each other doesn’t usually disappear, only changes. Studies show that couples in long-term relationships have the same level of dopamine as new couples, indicating that excitement and chemistry can still be evident in long-lasting relationships. 

If you’re still unsure if your connection has chemistry, speaking with a therapist may be helpful. Therapy, whether in-person or online, can help improve your communication skills, understand your relationships, and aid in personal growth. 

How to tell if you’ve lost chemistry in your relationship

Due to the natural phases of love, it’s common for chemistry to change in a long-term relationship. Most couples won’t feel the same level of passion beyond the early phases of a relationship. There is typically still warmth, affection, attraction, and chemistry. However, if there’s no spark, it could indicate underlying issues in the relationship. Some signs there isn’t chemistry in a relationship can be: 

  • An aversion to intimacy 
  • Not wanting or returning affection 
  • No desire to share personal details
  • Emotional disconnection
  • Spending a lot of time apart and it not bothering you 
  • Sensing that you’re growing apart 
  • Having romantic or sexual feelings for other people
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How to build more relationship chemistry 

Chemistry usually exists at the beginning of a connection and tends to lead us to choose certain partners. However, chemistry can develop slowly over time. For example, people may be lifelong friends who never really focused on each other until a chance situation. In general, though, if you don’t feel an initial spark or if you feel repulsed by someone, it’s typically an indication that you don’t have chemistry with them. 

Chemistry in a relationship can shift over time

In long-term relationships, chemistry may change over time. Couples may experience a reduction in the spark that was previously strong. In these cases, it may be helpful to intentionally try to rebuild their connection. For example, it may be helpful to break up your routine, schedule date nights, or try something new in the bedroom. Open communication and vulnerability can be key to rekindling chemistry. Going to a couples therapist may also help you reconnect and reignite your chemistry. 

Seeking support through online therapy

If fitting in-person therapy sessions into both of your schedules is too difficult, consider online couples therapy instead. With online couples therapy, you can attend sessions at a time and place that works best for both of your schedules. You can also attend therapy from the comfort of home, or anywhere you have an internet connection. 

Additionally, research shows that online couples therapy is as effective as traditional therapy at improving relationship satisfaction. A therapist can help you improve communication, work on intimacy, and solve any issues you may be experiencing in the relationship, all which could contribute to restoring chemistry. 

Takeaway 

Chemistry is an intense experience between people in relationships that may be caused by the chemical reaction happening in our bodies during the phases of love. There are many signs that you have chemistry with someone, but if you’re unsure or suspect you and your long-term partner have lost your chemistry, reaching out to a therapist may be helpful. 

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