5 Ways To Spot A Serial Cheater Within A Week Of Meeting Them, According To Psychology

Early red flags that quickly expose someone who has a pattern of chronic cheating.

Last updated on Sep 05, 2025

Serial Cheater. Krakenimages.com | Shutterstock
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Do you suspect your love interest is having an affair? Don't start making wild accusations just yet. Take a breath or two first. Even though you might have a gut feeling, these can be wrong. You don't want to ruin a potentially good relationship because you were feeling insecure. 

There are things to look for that indicate someone isn't likely to be faithful. Cheating across relationships definitely happens, as a 2017 study stated, "prior infidelity emerged as an important risk factor for infidelity in next relationships."

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Here are five ways to spot a serial cheater within a week of meeting them, according to psychology:

1. They spend more money than usual

Financial infidelity impacts relationships, according to research on love, lies, and money: "Romantic relationships are built on trust, but partners are not always honest about their financial behavior. They may hide spending, debt, and savings from one another."

Are they spending more money than usual, and you don't know where it's going? If they are taking a significant amount of cash out of their account, it could be a gambling problem, or payment for hotel rooms and gifts for others.

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RELATED: Keeping This Secret From Your Spouse Is Even Worse Than Cheating

2. They have a sudden change in behavior

Person notices change in cheater Cast Of Thousands via Shutterstock

If they start acting differently toward you, for instance, a lack of phone calls and no interest in talking or spending time together, this could indicate an affair. Research on infidelity showed how paying more attention to attractive alternatives to a relationship, combined with low self-control, creates a situation ripe for cheating.

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Positive changes can be a reason to be suspicious, too. They might buy you flowers without reason because they're feeling guilty. Try to question them about this sudden display of affection and see if they start to sweat under all that heat.

RELATED: 7 Red Flags On A First Date That Point To Someone Who's A Bad Person

3. They start working late

Too many late nights at work or business vacations without you are classic signs that someone may be having an affair. Next time they call and say they have to work late, offer to bring dinner to their office and see how they react. 

Try to ask them about any coworkers they have and see if they suddenly can't make eye contact with you.

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4. They change their appearance

Cheater changes appearance RobinE via Shutterstock

If your favorite couch potato has taken a new interest in fashion, grooming, and working out, they may be trying to impress another person. Of course, they might just be improving their lazy ways.

RELATED: 11 Phrases People Say Often When They Were Raised Without Boundaries

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5. You just have this gut feeling

The most accurate sign they are likely to cheat is your gut instinct, according to research in Frontiers in Neuroscience. If something just doesn't feel quite right, you may have good reason to believe they are being unfaithful. If you generally are not a jealous person, your gut feeling could be right.

Now what? No matter how many signs of an affair you find, you must confront them about your feelings and suspicions. Cheaters usually don't confess right away. You may be able to figure out what's going on by their reaction, though. 

Once you find out for sure that they are cheating, it's up to you whether you want to fight to keep them or walk away. Try to have concrete proof, like text messages or photos, because it will make it harder for them to deny it.

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RELATED: If Two People Truly Love Each Other From The Depths Of Their Soul, They'll Make These 6 Small Choices On A Regular Basis

Kori Ellis is a freelance editor and writer. She has been published in dozens of magazines, newspapers, and websites worldwide.

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