Solange reason for Punching and Kicking her brother-in-law @ Jay Z [See Gobe]

According to the New York Daily News, the blazing row was actually sparked by Jay Z, who snapped at Solange when two of her friends tried to get into the after-party at The Standard hotel in Manhattan by saying they were friends of the rapper.

And it was when Solange demanded that she, her superstar sibling and Jay Z leave the party that Jay Z said he was heading off to Rihanna's bash without Beyoncé, prompting Solange to hit out at him.

A source said Solange's pals '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.'
Jay Z soon got wind of it and snapped at Solange, saying 'don't use my name'. This in turn prompted Solange to insist that she wanted to leave the bash.
On the way out, Jay Z said he'd be heading to Up & Down on West 14th Street, where Rihanna was holding her own post-Met Ball bash, a second source said.
Allegedly, the star said he didn't need extra security because Beyoncé was not joining him.

The source said Solange, who seemed 'drunk and irritated', said: ‘Why can't you go home?' telling Beyonce 'Why does your husband need to go to the club right now?'"
But Jay Z replied: 'You're one to talk', which sent Solange into a rage.Once inside the elevator, she started punching and kicking her brother-in-law - an attack that was caught on surveillance video and leaked to TMZ.com on Monday.
Ultimately, the rapper decided against going to Rihanna's party and he was seen getting into a separate car as Beyoncé and Solange left together.
Jay Z and Rihanna are longtime cohorts. While president of Def Jam, he signed the Barbados beauty in 2004 and just days ago she signed to his label Roc Nation.She is also managed by Roc Nation.
Reps for Beyoncé, Jay Z and Solange did not return requests for comment.