“I get emails all the time from people in relationships who get blindsided by finding someone else attractive,” says Mark Manson, self-help author and personal development consultant. “They feel horrible because of it.”

But it’s irrational to beat yourself up over involuntary thoughts and feelings. Entering a relationship doesn’t switch off your normal biological functioning.

As advice columnist Mariella Forstrup puts it: “being in a long-term relationship doesn’t lobotomize the part of your brain that deals with attraction.”

“When we look at another person, our brain very quickly processes the visual information our eyes see, and we nearly instantaneously make a judgment concerning the other person’s attractiveness,” writes Gary Lewandowski, psychology professor and author of The Science of Relationships. “We can’t really help making these judgments; it’s automatic.”

Hence, even while in a relationship, you still recognize other people’s appealing features and characteristics (just as you did before you got with your partner).

In fact, “anything can make us suddenly notice someone,” says Ammanda Major, a senior consultant on sex therapy at Relate. A draw could be as subtle as a co-worker saying something that makes you laugh.

When it comes to doing right by your partner, what matters is how you act in response to the attraction — not the inevitable attraction itself.

As Manson reminds us:

Just because there’s no off-switch for attraction to other people, that doesn’t mean there’s something wrong with you or your relationship.

Evolutionary scientists have developed some interesting theories about why we might feel drawn to others — even if we’re happily taken ourselves.

Although we can’t change the biological basis of attraction, understanding it can help us respond more consciously to the impulses it creates.

After all, as psychiatrist Dr. Kenneth Rosenberg writes: “You can’t fix what you don’t understand!”