I was watching Wendy Williams this morning (it comes on after morning news...don't judge), and she was laying into Bill for apparently having a thing with Ann Winblad. They dated some time ago, but apparently have maintained a relationship where he visits her once per year. No way to know if it was sexual or perhaps a reason for the divorce, but apparently Melinda was accepting of it. At least early on, when Walter Isaacson wrote an article on the couple in 1997.
Williams also said that the kids are more on Melinda's side.