Justin Bieber, Miranda Kerr sexy hotel rendezvous? 'Heartbreaker' parties with Orlando Bloom's ex at Lavo nightclub after Victoria's Secret Fashion Show, kinky hook-up?

Miranda Kerr and Orlando Bloom are no longer together - and rumors suggest "Heartbreaker" crooner Justin Bieber might be to blame...

As Mstars previously reported:

Earlier this month, reports confirmed that Victoria's Secret beauty Miranda Kerr and "Pirates of the Caribbean" heartthrob Orlando Bloom were separated. A rep for the ex-couple released this official statement:

"Orlando Bloom and Miranda Kerr have announced that they have been amicably separated for the past few months. After six years together, they have recently decided to formalize their separation."

Rumors even suggested that Bloom was cheating on his wife with "Romeo & Juliet" co-star Condola Rashad - check it out:

Orlando Bloom and Miranda Kerr separate, actor 'cheating' with 'Romeo and Juliet' Beauty Condola Rashad? [PHOTOS]

But NOW rumors have it that 30-year-old Kerr was actually the one perhaps cheating... with 19-year-old "Believe" crooner Justin Bieber!

An alleged source for Us magazine claims that the gorgeous model was "always very flirty" with Selena Gomez's ex. The duo hung-out backstage after last winter's Victoria's Secret Fashion Show. Apparently, they even started "sexting" and sending flirty messages to each other!

Another insider tells The Mirror, "Orlando heard that there had been some ­flirting ­going on and he wasn't exactly thrilled about it."

So that put some tension on their marriage and the couple started fighting a lot - and now they're headed for divorce.

Interesting...

FYI - when Bieber and Kerr started "flirting," the Biebs was still dating Gomez... if only those "kinky" texts would leak online if the rumors are indeed true!

Now, InTouch magazine claims that things probably got REALLY hot-and-steamy between the duo.

Following the fashion show last year, Bieber and Kerr were spotted partying together at Lavo nightclub. Innocent enough... but according to the infamous gossip rag, their night didn't end there...

Kerr allegedly told a model friend that she met up with Biebs at his hotel following the party... no details about what went down behind closed doors though. It remains unknown where the duo went, or if Kerr actually spent the night. But what do Mstars readers think? Did Bieber and Kerr ever "secretly" hook-up?