Wall Street Journal:

The split between Bill and Melinda Gates, announced last week, has been in the works for a long time. Melinda consulted with divorce lawyers about two years before it was publicly announced, saying their marriage was "irrevocably broken," according to sources familiar with the matter and documents reviewed by The Wall Street Journal.
According to the Bill & Melinda Gates Foundation, "one of the sources of Melinda's concern was her husband's relationship with a convicted sex offender" and committed suicide in prison " billionaire Jeffrey Epstein. Ms. Gates ' concerns began in 2013."