Ekin-Su Cülcüloğlu is said to be "furious and really upset" after finding messages from her boyfriend Davide Sanclimenti to two models, according to reports.
The Love Island winners are said to have gotten into an argument after Ekin-Su found the messages on Davide's phone, with the 28-year-old reportedly contacting one of the women herself.
Davide is said to have met up with Instagram influencers in Manchester, before messaging the women to discuss their time together.
Ekin-Su is thought to have then found the messages after returning from a trip to Belfast.
A source close to the pair said: "It all exploded last Sunday after she found messages on Davide’s phone discussing their time together.
"He had been messaging both of the girls and she suspected they had all met up one night."
Speaking to The Sun, they added: "Ekin-Su contacted one of the girls to tell them she knew about things. She was furious and really upset."
Ekin-Su's reps declined to comment when approached by the Mirror.
The Mirror has also approached representatives for Davide for comment.
The alleged bust-up comes after fans started to fear for the pair's relationship following a veiled swipe at "disrespect".
On April 3, Dancing on Ice star Ekin-Su liked a tweet which read: "Distance is my new answer to disrespect.
"I no longer react, I no longer argue, I no longer dive into drama. I simply remove my presence."
On February 23, she also liked a post that said: "People be turning out to be exactly who they said they weren't."
Fans are now suspecting whether it could be the end for Davide and Ekin-Su.
One person tweeted: "Wait Are Davide and Ekin Still together?? Cause why are some of their fans crying on Twitter and Ekin liking indirect tweets about being disrespected and lies I'm confused."
Despite the rumours, Ekin-Su and Davide were spotted on Thursday jetting off together on a trip to Amsterdam.
* Follow Mirror Celebs on Snapchat, Instagram, Twitter and Facebook.