Justin Bieber & Kourtney Kardashian Hook-Up Gets Hotter: Selena Gomez & Scott Disick’s Shocking Reactions

Justin Bieber and Kourtney Kardashian succeeded in winding up this year with a rise to the top of the Hot Celebrity Hook-Ups list. With 21-year-old Justin the pop idol and 36-year-old Kourtney the reality TV star having their steamy romance confirmed by multiple media outlets’ sources, Bieber and Kardashian are having flirty fun while enduring rumors of some outrageous responses from his ex Selena Gomez and her ex Scott Disick.

So how did the romance between Justin and Kourtney begin? Travel back to autumn, when Kardashian and Bieber were spotted out on a date, revealed Us Weekly.

“Justin bragged to friends recently that he has been hooking up with Kourtney Kardashian,” a source told Us.

Kourtney attended the American Music Awards after-party that Bieber enjoyed in Los Angeles last month, and another insider confirmed to Us that Bieber and Kardashian were definitely a hot item.

Justin Bieber is enjoying flirty fun with Selena Gomez.

Whether it’s a hot place in Hollywood or a karaoke lounge, the affectionate couple just can’t seem to stay apart.

“Kourtney and Justin seemed flirty,” one observer shared with Us. “I saw them a few times touching and laughing together.”

And that’s definitely not all. The timeline of hot hook-ups between Kardashian and Bieber includes a spotting of Kourtney at a Beverly Hills hotel frequented by Justin. She stayed there until 4 a.m.

Kardashian and Scott Disick have three children, and she ended their relationship in July. Bieber broke up with Selena Gomez previously. When Kourtney and Justin have been observed on dates, Bieber is clearly trying to make a good impression on the new older woman in his life, an insider told Us.

“[Justin] was such a gentleman and so nice and respectful,” added that insider. “He was definitely trying to impress Kourtney and act more mature.”

Bieber has even served as the baby-sitter for those three children parented by Kardashian and Disick. Adding to his inner edge with the Keeping Up With the Kardashians clan, Kris Jenner is dating Corey Gamble, who is Justin’s pal and former tour manager.

But while Bieber is enjoying his flirtation with Kourtney, Justin’s ex Selena Gomez is irate, according to Hollywood Life‘s insider.

Selena Gomez is stunned by the romance between Kourtney Kardashian and Scott Disick.

“Selena can’t seem to get past the fact that Justin is dating Kourtney Kardashian. She talks about it all the time. At first she was shocked and didn’t believe it, but then she started to think about it and realized the writing was always on the wall. He’s always had a thing for older women.”

That same source also revealed that when it comes to Kardashian women, Justin rated Kourtney on top. But Selena viewed it as a boyish crush, never imagining that it would turn into a real romance.

Justin Bieber causes problems for Scott Disick.

The insider claims that Scott chose to get back at Justin by giving a gift of gold-plated poinsettias to Selena. In addition, Disick invited Gomez to his Las Vegas party bash he’s hosting on New Year’s Eve.

“Scott’s really gunning for Selena. He won’t stop until he’s victorious in one way or another,” added the insider cited by Ace Showbiz. “She’s yet to respond and Scott’s not sure if she’s received his gift. But he’s certain that lady Gomez can’t resist his charm.”

However, a different report quoted other insiders describing those rumors about Disick and Selena as fiction rather than fact.

Who do you believe when it comes to the rumors about Justin and Kourtney? Do you think Scott really is trying to woo Selena as a revenge? Post your views below.

[Photo by Michael Loccisano/Getty Images]