Nadine Leopold reportedly dumped Harry Styles because she feared that he was being unfaithful to her.

Heat magazine (via SugarScape) recently reported that the supermodel had to break up with the One Direction member due to her hectic schedule.

"Nadine is really career-focused and she's told Harry she's simply too busy to date him," a source revealed. "Harry is gutted. He's never been dumped before, so it's a real punch in the stomach for him. Even though they couldn't spend much time together, Harry was speaking to her a lot and making plans to fly her over to spend the summer with him."

However, according to HollywoodLife.com, Leopold was allegedly worried that Styles was cheating on her while apart. A source claimed that the One Direction singer is always "swarmed by gorgeous women." And perhaps what really concerned the model is that Styles is reportedly a "major flirt." 

"Most of the time, it's harmless and he's just being playful, but it definitely affected Nadine," the source said. "She was convinced he was cheating while on tour."

As a result, although she did not have any evidence, the blonde beauty ended the long-distance relationship with the "Steal My Girl" singer.

"She has no proof except for circumstantial evidence like hearing girls laughing in the background when they talked on the phone or him having his phone turned off for long periods of time," the source alleged. 

Another source added that things did not work out between the two because Harry Styles "didn't make Nadine feel safe and secure enough in their relationship."

"Nadine wanted a more serious commitment from Harry," the source told HollywoodLife.com. "She felt like he needed to make more an effort to see her. She just didn't feel like he was taking their relationship seriously enough, and basically she doesn't have time for any games in her life."