The rapper, whose marriage to Beyoncé is reportedly on the rocks, originally didn't plan to attend the ceremony with their daughter, Blue Ivy, two, last Sunday (24.08.14), but felt he had no choice in the end.
A source close to the 'Empire State of Mind' hitmaker said: "Jay didn't want to go, but it would've confirmed rumours."
The couple put on a united front, with the 'XO' singer calling her husband "my beloved" on stage, but the insider claims they are still planning to divorce.
The source said: "They are splitting in a few months.
"Even Bey calling Jay 'my beloved' was preplanned."
Meanwhile, Kim Kardashian West is also reported to not have been keen to bump into Beyoncé at the event.
The 'Keeping Up with the Kardashians' star, 33, still hasn't forgiven the 32 year old for skipping her wedding to Kanye West in Florence, Italy in May, and didn't make any effort to speak to her at the ceremony in Los Angeles.
A source told gossip website RadarOnline.com: "Kim blames Beyoncé for Jay Z skipping their wedding. Kanye considered Jay family, and the last minute decision for him to not come to their wedding was extremely selfish."
The insider added: "[Kim] thinks that that Beyoncé has always been very arrogant and aloof around her. Kim always made a real effort to get to know her and Jay, but she was always left with a very cold feeling. Beyoncé made Kim feel very insecure and that isn't something that she is used to."