The 'Turn Up The Music' singer's partner Karrueche Tran witnessed the
display of affection along with a television audience at the Staples
Center in Los Angeles, California.
Apparently the 23-year-old aspiring model is "totally pissed off" with her boyfriend of almost one year for allowing the peck after winning Video of the Year at the annual gathering.
A source told UsMagazine.com: "She felt the kiss was a public slap in the face."
Rihanna, 24, and Chris parted ways in February 2009 after he brutally assaulted her and have more recently been rumoured to have rekindled their romance.
The insider added: "[Karrueche] and Rihanna really hate one another and Chris ultimately just does what he wants.
"Seeing him with Rihanna at such a public event made her very angry."
Rihanna recently opened up about her complicated feelings for her ex to Oprah Winfrey, calling him "the love of my life" as she was interviewed for her television show 'The Next Chapter'.