It may have been months or years since the last time you saw your ex. You may even be completely over them at this point. But for some reason, running into an ex always feels so weird. From the moment you spot them from afar, you can’t help how your body reacts. You might tense up, your heart might start to race, and you may suddenly feel the strong need to run away and hide. If you ever wondered why you can’t ever just stay cool in this type of situation, there’s a really good reason why.

"Running into an ex brings up a variety of emotions, and emotions are often visceral and powerful reactions that the body can't always rationally explain or control," David Bennett, certified counselor and relationship expert, tells Bustle. So it doesn’t matter how much time has passed or how you feel about your ex at the time, running into them unexpectedly can still cause physical reactions like increased heart rate, sweating, stomach cramps, or a tightness in the chest.

It can be a little confusing to react so strongly to someone, especially if you know you’ve moved on. But according to Bennett, it’s normal and usually not something to dwell on. “We are not simply our emotions,” he says. “Our frontal lobes, which are the logical parts of our brains, are very powerful. Since this is visceral emotion, it's not necessarily an indicator of anything.”

In other words, the physical reaction you get from seeing your ex doesn’t always mean you’re still in love. But it can make you want to run away. According to experts, there is a reason for that.

Running Into An Ex Can Trigger Your Fight Or Flight Response

Seeing your ex in public out of the blue can give you a little bit of a rush. As Dr. Laura Dabney, M.D., psychotherapist who specializes in relationships, tells Bustle, that feeling you get is likely a symptom of anxiety. “When you haven't seen or been around an ex for a bit and you see them for the first time, the rush tends to be the manifestation of the anxiety or nervousness you may be feeling,” Dabney says.

In fact, Elsa Moreck, certified dating coach who specializes in helping millennials, tells Bustle, "Your body doesn’t know the difference between running into an ex and running into a bear. So when it does happen, your gut reaction may be to get out of there quick."

While bumping into your ex out of nowhere isn’t nearly as dangerous as a bear coming at you, it can still trigger the body’s stress response, or freeze, flight, or fight mode. According to Moreck, depending on the quality of memories that you have with them, any of those three automatic responses may dominate.

Ultimately, your body wants to protect you from harm. Breakups can be very painful experiences. In fact, a 2010 study published in the Journal of Neurophysiology found that the part of the brain that registers physical pain was activated when people were just shown photos of their ex. When your stress response is triggered by running into them somewhere, the instant panic you get might cause you to turn around and go the other direction.

If you still have an emotional attachment to your ex, Jude Treder-Wolff, LCSW, a therapist who specializes in stress-resilience and self-care, tells Bustle, you can even have a full-blown stress response just because of the emotional stakes involved.

Anger and unhealed wounds can also trigger the stress response, and can make you either run away or “fight” by expressing your feelings to your ex.

What You Can Do In This Situation

There's no way to really control how your body reacts to seeing your ex unexpectedly. But you can control what you choose to after. According to Moreck, try practicing mindfulness.

"Mindfulness is the little space you have in between a stimulus and a thought," Moreck says. "It’s what happens when that 'oh no!' moment is about to take over, but somewhere else inside that squishy muscle of yours is another thought that’s like, 'well, I'm technically not going to die from this'.”

When you recognize that you've just spotted your ex, you can choose to reframe the situation in your mind. Consciously decide to take a deep breath in order to relax a bit, put a smile on, and then face your ex with confidence. "Let go of the past and appreciate them for whatever crossing their path has taught you," Moreck says.

Running into an ex might make you want to hide, and that's all thanks to your body's stress response system. It's not something you can really control. What you can control is how your mind perceives the situation and what you do in the moments after.

Study Referenced:

Fisher, H.E., Brown L.L., Aron, A, Strong, G, & Mashek, D. (2010) Reward, addiction, and emotion regulation systems associated with rejection in love. Journal of Neurophysiology, https://www.ncbi.nlm.nih.gov/pubmed/20445032

Experts:

Elsa Moreck, certified dating coach

David Bennett, certified counselor and relationship expert

Dr. Laura Dabney, M.D., psychotherapist

Jude Treder-Wolff, LCSW, creative arts therapist