Beyonce vs. Rihanna beef intensifies, cheating scandal erupts: Solange 'attacks' Jay-Z, rapper wished to party with Drake's girlfriend 'alone'

Well, well, well. Turns out Solange Knowles probably "attacked" Jay-Z in a hotel elevator all because of Beyonce's on-and-off again rival, Rihanna!

Most Mstars fans have probably already witnessed the epic beat-down footage, but for those who haven't...

Pretty crazy.

So, why exactly did Solange violently punch and kick her brother-in-law? That still remains a total mystery, but here's an idea...

HOV wanted to party with Rihanna after NYC's annual MET Ball Gala - solo!

According to the New York Daily News, Jay wanted to keep the good times rolling - without his "Drunk in Love" wife.

Ouch.

The infamous gossip webloid reports, "Tensions were already running high when Jay Z - while walking to the now-infamous Standard Hotel elevator - said he was going to the Rihanna bash rather than heading home with Beyoncé."

Jay and Solange were already arguing earlier on in the evening:

"Two of her friends, who were not dressed for the Met Ball, showed up at the Standard and caused a scene downstairs," an insider reveals. "They wouldn't leave and kept name-dropping Jay Z. They were pretending they were guests of his and not hers. Management went to Julius (Beyoncé's bodyguard) and said there's a problem." 

The rapper got tired of all the drama, so all three prepared to leave. 

But HOV didn't want to go home - he was ready to continue partying at RiRi's gig at Up & Down nightclub. Alone.

So when leaving Manhattan's swanky Standard Hotel, Bey's "intoxicated" younger sister exclaimed, "Why can't you go home?"

But the Magna Carta rapper wasn't hearing it.

Doesn't help that rumors already suggest that HOV may have had a little sexual "fling" with Drake's girlfriend in the past...

What makes things worse - Jay's posse already called ahead to Rihanna's crew, explaining that they "didn't need extra security" because Bey wouldn't be attending.

So following Solange's repeated taunts, she eventually told Blue Ivy's baby mama, "Why does your husband need to go to the club right now?"

Jay didn't like the aspiring songstress getting all up in their personal business, so a heated argument ensued. The rapper made one harsh comment while stepping into the hotel elevator, and she attacked.

Allegedly.

Wow - do readers believe that!?