Kelly Rowland reportedly sometimes gets a sense "that life wasn't fair".
Although the singer has enjoyed a solid career, she apparently can't help comparing herself to her former bandmate Beyoncé Knowles. The pair both found fame in Destiny's Child, although Beyoncé is regarded as a more successful solo artist.
"They're both singers and every once in a while I think Kelly feels a sense that life wasn't fair and it gets to her," a source told Heat magazine.
In February, Kelly was seen crying after enjoying lunch with Beyoncé. It was claimed her former bandmate had dismissed the idea of recording another record with Destiny's Child, which was rumoured to be in the pipeline after Kelly and the band's third member Michelle Williams joined Beyoncé on stage at the Super Bowl earlier this year.
More recently, Kelly burst into tears while performing her track Dirty Laundry - which seemingly references the jealousy Kelly has felt towards Beyoncé.
"Kelly loves Beyoncé so much, but for her entire life it's like everything always came easy for Bey, whereas Kelly hasn't had it so good at all," an insider explained.
"It's a complicated relationship. Kelly was so envious of the close-knit Knowles family and then, when Bey went on to have a massive solo career and to have a wonderful relationship with Jay-Z and a baby, I think for a while, Kelly felt a bit lost."