A British woman has gone to extreme lengths to uncover whether her boyfriend was cheating on her after she found a wrapped tampon that wasn’t hers concealed in his home.

Lois Saunders, 23, took to TikTok on Monday to reveal she found the menstrual product alongside a tube of mascara stuffed under a closet in the college dorm room of her lover, Finn.

“I’ve just found a tampon and a mascara under Finn’s wardrobe, and he’s in denial that he’s had a girl here,” Saunders states in the clip, which has gone viral on the social media site.

Finn claimed he had no idea who the sanitary item belonged to, saying it must have been left behind by the dorm’s previous occupant.

In the clip, a jilted Saunders is seen reaching for the Tampax stuffed in a crack under the closet, saying there isn’t enough dust on it for it to have been lying there for a long period time.

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In a move that would surely impress Nancy Drew, the brainy blond decided to contact Tampax manufacturer Procter & Gamble and send Tampax the serial number on the box to find out when the tampon was made.

She shared screenshots of her correspondence with the companies in the TikTok clip.

“Hello. What is the code on the side of the individual tampon for?” Saunders asked in an email to P&G customer service. “I have a tampon with the code 93452080N2. It’s yellow; regular. Can you tell me when this was manufactured? … I am doing some investigation.”

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Saunders and her boyfriend, Finn, are pictured in an Instagram photo.

A Tampax representative soon responded to Saunders’ email, writing: “Based on the code … the tampon was made December 11, 2019.”

The rep added that the tampons do not have an official expiration date, but have a shelf life of five years.

Saunders told her TikTok followers that the date of the tampon’s creation far preceded the date that Finn moved into his dorm room, and she was seemingly satisfied that her man was not cheating on her.

“We were just laughing about it together, because it was a bit of a joke,” Saunders said in a follow-up video, revealing that she had only recently begun seriously dating her beau.

“He had obviously never swept under the wardrobe … I believe him. We are still together, and very happy!” she further declared.

However, some of Saunders’ followers weren’t laughing at her behavior, with one even branding her a “borderline psycho.”

“Finn, run! Red flag!” one male viewer wrote.

“There’s nothing that men hate more than a woman who not only doesn’t trust, but then goes snooping. Because she has to be right,” another man commented.

A third bluntly stated: “This is why I’m gay,” and a fourth mused A third added: ‘I’m not sure if this is genius or borderline psycho.”

However, there were thousands of other followers who were wowed by Saunders’ sleuthing.

“If I ever get kidnapped, ask her to solve my case!” one impressed fan wrote.

Another chimed in: “The lengths us girls go to. Men have no idea what we’re capable of. They could never.”

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The happy couple are still together, despite the fact some say Saunders’ detective work has not absolved Finn completely.

Meanwhile, some were left unsatisfied by Saunders’ detective work, claiming it did not necessarily absolve Finn of infidelity.

“DNA fibers from the mascara is the only next possible step,” a viewer hilariously quipped, mocking Saunders’ elaborate investigation.

Per: NYP