My guess is, barring any pedo revelations or other revelations hitting the fan, the two of them had a power struggle over the foundation, how they're going to proceed with world domination via global vaccinations and passports, and how they're going to avoid being blamed for the consequences.

It's quite possible there were/are serious affairs with others behind the scenes as the two of them lead separate lives despite appearances.

She's known to be bossy and wears the pants in the marriage and was the one who was pushing the global health and vaccination agenda all these years. Bill went along with it.

Under her domination he went from being one of the most admired men in the world to the most hated and is a target. I'm sure they've both been miserable the past year with all the hate and threats they and their family have been getting and it's put a huge strain on them. So somebody wanted out.

I kind of doubt they did it for tax reasons like some say Bezos did. I don't believe Bezos and his wife divorced for taxes but because their marriage was totally over and they found lovers they wanted to spend their lives with. His wife just married a chemistry teacher who taught at the private school their kids went to. The same private school (Lakeside) that Bill Gates attended as a kid.