Curtis Pritchard and Amy were initially one of the frontrunners to win the show - but the ballroom dancer strayed from the 26-year-old former air hostess while she was put in neighbouring villa Casa Amor.
In Tuesday night's episode, he tried and failed to woo Vogue model Jourdan Riane, leaving him recoupling with Amy by default.
She was blissfully unaware of his actions as she confessed her love to him for the first time to other islanders.
In Wednesday night’s episode, the fallout of his actions came out as he confessed everything to her.
He said: "I'm going to be completely truthful with you about everything.
"I pulled one of the girls for a chat, I spoke to her and she said, 'if there was a recoupling in half an hour, would you recouple with me?'.
A furious Amy interjected: "Yep, carry on the story. So recoupling was in half an hour...?"
"And I said I'd recouple with her," Curtis said, before admitting Jourdan said no.
Amy said: "So she said no, so you were like, 'ugh, right then, I'll go back to Ames'."
In the Beach Hut confessions room, Curtis told the cameras: "I've messed up. I've hurt her, treated her very bad. I've been disrespectful."
Amy did not hold back with how she felt to Curtis.
She said: "I fell in love with you and I get back to this. I never thought you would do this to me. You're the perfect man, after all.
"Do you know how worthless this makes me feel? To know that you didn't like and respect me enough to be able to resist makes me feel like utter s****."
The whole exchange left Amy distraught. Fighting back the tears in the Beach Hut, she said: "I thought I'd met my first love and 'the one', and it turns out I haven't.
"I'm someone's back-up plan yet again."
The couple slept apart from each other, with Curtis taking one of the day beds outside and Amy seen crying the following morning.
In a preview for Thursday night’s episode, Amy accuses Curtis of being a liar.