This wasn't something I overheard on my own, more of a collective work of overhearing of my team that we pieced together afterwards via half heard conversations, weird things that happened and the company suddenly not doing well.
I worked in the office of a small construction company, only about 30 of us with two company owners.
One of the owners was my manager and quite a dick had had an affair years before, left his wife with two small children etc etc married the new woman has another child yada yada. He was constantly CONSTANTLY going on about how crap first wife was, how fat and ugly she was and how slim and gorgeous new wife was how amazing they were together etc.
New woman was nice enough and occasional came into the office to help out and was getting more involved in the work. After I had been there a year then boss started acting different, bad mood, moping etc etc then we started hearing bits and pieces. Him on the phone with her, him on the phone with his business partner (close the door for god's sake!) we started to have trouble paying our invoices, and we all started comparing notes.
Turns out the new woman was having an affair. That made boss man mope for months and months but the shit didn't hit the fan until he admitted it to his business partner.
You see, they had dodged tax by putting a big chunk of the company in her name. She was 20% owner and now boss has to tell other boss that she was leaving and they had to buy her out. Other boss was refusing to sacrifice any of his own stake and that my boss would have to give her the house in order to keep the company etc etc. Glorious.
It was months of intrigue and was great for us as suddenly he stopped micromanaging us and we could just get on with our work. Most productive quarter ever.