Writing in a post on metafilter.com, the heartbroken 23-year-old revealed that she had been dating an older man for over a year and a half - and that, before that, she had been his friend for three years.
They had met while he was studying abroad at her university, so the relationship was long-distance - but the pair always found time to stay in touch, despite the miles between them.
But, while trawling through Facebook, the young woman (going by the name sock puppetry) stumbled upon photos posted by a friend of his that appeared to show him getting married to his ex-girlfriend.
Never a good sign.
She explained: “They look so real; he and his ex are both in gorgeous wedding attire and there's a crowd in the background and I just don't know what to think.
“There was even a framed family picture of them in one of the photos!”
But, when sockpuppetry confronted him about the photos, he claimed that they were "from a video that his university is making for new students to show how glamorous graduate school life can be."
Utterly confused, she asked the internet for help, begging: “He couldn't possibly also be married, right?
“I feel like I'm overreacting, but how do I tame my irrational fears?
Almost immediately, sockpuppetry received an overwhelming response from cynical readers - all of whom called B.S on the guy’s lies.
One wrote: “You are NOT being irrational or needy. This is VERY weird and you have every right to ask. A proper boyfriend will take you seriously, not make you feel bad.”
Another added: “I’d make him get the photographer and the ex to corroborate his story, because if the story is real, they should be eager as hell to make sure that you understand it was all fake.”
"Contact his wife. This is psycho level deceitfulness," one insisted.
As you may have guessed, this story did not have a happy ending.
She challenged her man angrily - and he finally admitted that he was engaged.
The pictures she’d seen were actually from his hideously swanky engagement party.
She wrote emotionally: “I’m angry and heartbroken, and I don't know what to do when part of me is so betrayed and the other part still loves him.
“Crazily enough, that part of me that cares about him is even a little glad that he found someone he really loves. But I don't know what my tomorrow morning will be like without a good morning text from him, without hearing his voice.”
We hope that she has a good support group around her, and that she realises that she’s far better off without this creep in her life.