Kim Porter left P. Diddy after he fathered another woman's child.

Porter, who has three children with the hip-hop star, admitted their romance
imploded when she discovered Diddy had a child with a mystery woman in
Atlanta.
When asked if the rumors of a secret baby were the reason Porter ended
their relationship, she told Essence magazine: "That definitely was part of
it."
Diddy was reportedly desperate to keep the baby a secret from Porter - who
was pregnant with their twin girls at the time - and allegedly paid the
unnamed mother $1 million to stay quiet.