I’d never even heard of the “second calculator” app…until now.

As a full-time writer at BuzzFeed, I cover books, relationships, sitcoms, and all things pop culture.

"Or finding a hair that’s not yours on their p*nis. (This happened to me!)

"All of a sudden, showering before they see you, and immediately after they see you." 

"When they have a new taste in music, all of a sudden."

"If they start talking about someone else a lot, even if they say they dislike them."

"Running out to do some errand or go to the gym, etc., and gone much longer than seems reasonable."

"Started leaving sooner for work, and started coming back later."

"Sometimes they can be nice, so nice. He’s sweet, responsible, and makes you feel like you’re the one. But still, something in you feels like something is wrong. Even though you’re being treated right, something just doesn’t sit well. Always trust your instincts, no matter how good or beautiful things seem." 

"Suddenly buying new clothing, underwear, and fragrance." 

"When they suddenly start shaving their pubic hair when they never did that ever before."

"If they start accusing you of cheating seemingly out of nowhere and getting mad about it, they're probably projecting, and the one who is cheating on you."

"That's exactly what my mother did before cheating on my father. She lost a bunch of weight, got plastic surgery, and started dressing very nice — all paid for by my father, — just for her to cheat on him and then accuse him of being paranoid when he started to suspect she was seeing someone else." 

"She goes shopping all the time but seldom brings anything home." 

"The sudden, aggressive 'love bombing' out of nowhere is a red flag. If they’ve been distant or just 'normal' and suddenly start acting like a hopeless romantic — buying random gifts, being extra clingy, and overcompensating with affection, it’s usually guilt." 

"Some people can just have a bad week, but if the change of behaviour is prolonged, dig deeper." 

"They’re always on their phone but don’t text you as much, and when they do text you, it’s like they don’t care." 

"Disabling phone notifications, switching windows or closing apps as soon as you walk in the room, always have their phone close to them."

"They stop sharing random little details about their day. Conversations feel surface-level, like you’re talking to a coworker instead of your partner. You notice they’re suddenly 'too tired' or 'too busy' for things you used to do together, but somehow they still have energy for everything else."

"It was that he stopped wanting to cuddle at night, started facing away instead of spooning. The 7-year marriage was over within the month." 

"If they start attending several clubs or classes a week, and leaving you to babysit."

"They get annoyed with you when you ask why they are spending so much time with another person." 

"He started treating me really nicely. I had assumed he was just maturing and growing out of his insecurities. I found out a few months later that they were just overcompensating because they were cheating. They hadn’t become any less controlling or jealous; I just wasn’t his focus anymore." 

"I found out by going through my analytics and data. I would search up his usernames, emails, and his phone number — and Tinder profiles attached to his email and phone numbers showed up."

Note: Some responses have been edited for length and/or clarity.