Insiders claim the REAL reason Solange attacked Jay Z inside the elevator after the Met Gala is because he planned to go to Rihanna’s Met Gala after party without Beyonce…

From The NY Daily News

Beyonce’s sister went berzerk on Jay Z after the rapper insisted on going to Rihanna’s Met Gala after-party, the Daily News has learned.

But the fight that led to the Standard Hotel elevator explosion was set in motion 15 minutes earlier when a group of Solange Knowles’ non-famous friends showed up uninvited at the star-studded soiree, a source told The News.

“Two of her friends, who were not dressed for the Met Ball, showed up at The Standard and caused a scene downstairs,” the source said.

“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 (Beyonce’s bodyguard) and said there’s a problem.”

Our source said Jay Z soon got wind of it and snapped at Solange, saying “don’t use my name.” The 27-year-old singer turned sullen and said she wanted to leave the party.

On the way out, Jay Z said he’d be heading to Up & Down on W. 14th Street, where Rihanna was holding her own post-Met Ball bash, a second source said.

Jay’s camp had called ahead of time to say he would be coming alone and “didn’t need extra security” because Beyonce wouldn’t be attending, the source said.

Apparently, that didn’t sit well with Solange.