There have been so many stories, it's hard to pick something to believe. But the Yoko theory does make sense. Tom told Gisselle what was going on and she didn't like it. In fact, Giselle started speaking for Tom as described in this meeting with Bob Kraft where the origin of "Johnny Foxboro" began. Bob set up a meeting when Tom initially stated he wanted out after the 2017 Super Bowl loss to the Eagles:
"Soon after, Benedict writes, Kraft summoned Brady and his wife Gisele Bündchen to his home for a discussion. Bündchen took up for Brady. After pointing out how much Brady had done for the organization:
She also pointed out how ridiculous it was that after all these years, Belichick still treated Brady like "f****** Johnny Foxboro." It was bad enough to never voice approval. It was ******** to still be dressing down the most accomplished quarterback in league history during team meetings and treating his personal trainer and best friend like some kind of outcast.
When the conversation shifted to the future, Brady and Bündchen indicated it was time for them to make some changes that were in the best interest of their family. Among other things, they were contemplating a change of scenery."
As the article later points out, Bob was initially reluctant to allow Tom to leave, but later agreed if Tom still wanted out. Tom decided to return to NE under his conditions. This was why he was absent during the 2018 off-season. Bob was also going to lobby with Bill to "lighten up". Meanwhile, BB had a trade in place with Detroit for Gronk which not only pissed Gronk off, but blocked the trade.
Tom Brady eventually left the Patriots after 20 seasons and six Super Bowl titles, but as Tom E. Curran writes, Brady's exit almost took place two years earlier after a Super Bowl loss to the Eagles.
sports.yahoo.com