Justin Bieber's fling with Kourtney Kardashian is an 'ego boost' for him.

Justin Bieber

Justin Bieber

The 21-year-old singer has reportedly been hooking up with the 36-year-old mother-of-three and is thrilled that she is interested in him.

A source told PEOPLE: "He has had a huge ego boost from hooking up with Kourt. It's been going on for a few months. He is used to being swooned by young girls that have nothing else going on. Kourt is a hot mom with a career."

Kourtney's former partner Scott Disick, 32, the father of her three children, is said to be furious at the fling and believes she is only using Justin to get back at him but the 'Sorry' hitmaker doesn't care.

The insider said: "He more thought, 'Wow,' and couldn't believe that she would go for him. He brags about how hot she is. He is happy while it lasts. Even if she is using him to get back at Scott, he couldn't care less."

"He's obviously close to the family, and Kris [Jenner] is obsessed with him. It's just one of those things where it makes Kourtney feel good about herself. It's not serious at all. This young guy is into her, he thinks she's hot and she's older. She just wants to have fun."

Tagged in