After reading this story:
http://news.yahoo.com/s/ap/20061110/...e_shar_jackson
I'm thinking if this was really part of a master plan.
KFed's broke and Shar's not making much from Moesha syncation royalties. Kevin notices Britney has the hots for him and devises a plan to get her $$$$.
KFed leaves Shar temporary and gets with Brit. They get married, knowing that regardless, he (and Shar) are about to get paid.
Now that Brit has saw the light of day, he figures he will get full custody to get the money rolling (for at least the next 18 years). Shar winds up back in the picture and they don't have to work again because they are living off of Brit's $$$$.
I probably though too much about this.