Sources say that Vanessa decided to end the marriage because she thinks the Los Angeles Lakers guard has been unfaithful ... and not for the first time.
As one source close to Vanessa put it, "She's been dealing with these incidents for a long time and has been a faithful wife, but she's finally had enough."
"This one is the straw that broke the camel's back."
Kobe Bryant, WifeVanessa Bryant
Vanessa Bryant famously stuck by Kobe after he was charged with sexually assaulting a Colorado woman in 2003 (he was acquitted of all charges).
Apparently the cheating didn't end there, though, and while Kobe "desperately" wants to win her back and will do "whatever it takes" ... good luck.
Vanessa is asking for joint custody of their two daughters, Natalia, 8, and Gianna, 5, but is asking that the basketball superstar get visitation rights
There is no prenup, so 29-year-old Vanessa is entitled to half the empire built over the last decade by NBA MVP and five-time champion Kobe, 33.
She's also requesting spousal support, which Kobe will pay. The Bryants released a joint statement saying they have "resolved all issues" privately.
No word on whether Kobe plans on changing his uniform number yet again or if Vanessa plans on joining the new season of VH1's Basketball Wives.
SIDE NOTE: That $4 million ring Kobe gave Vanessa after the 2003 scandal - later referred to as "the Kobe special" by Tiger Woods - all hers. Gift, babe.
[Photos: WENN.com]