AceShowbiz -

It seems like Justin Bieber and his new girlfriend Haily Balwin are going strong. An insider told HollywoodLife.com that the 21-year-old singer adored the model so much for several reasons. And guess what, her lips may be the main reasons why Bieber is deeply in love with her.

Since the pair are no stranger to PDA and have been spotted kissing several times, it's not surprising that the model's lips are one of Justin's favorite part about her. The insider added that Justin just couldn't stop kissing the 19-year-old model because of her tempting lips. "Her lips are a big turn on for him too, he loves kissing her. She's just hot in every way, he thinks she's gorgeous," the insider said.

However, that's not the only reason that made Justin fall in love with Hailey. "It's not just her looks that make him want to be with her, he thinks she's beautiful, but her personality is a big part of it too," the insider shared. "She's hilarious, she can have him and his friends laughing, she can definitely keep up with the guys when it comes to her sense of humor."

The fact that Hailey is a "low-maintenance" girl who could "throw on anything and be ready to go in five minutes and still look gorgeous" is another reason Justin is enamored of her.