I actually don't watch much MMA anymore. I did see the season of TUF that McGregor was on and didn't like him because he was arrogant, same as Ronda. On that show you see a lot of how they interact with other guys. He was generous with the fighters he liked, but he was always walking around making it clear he was better than all the rest because he made more money.
Ronda always seemed to be on a hair trigger. It didn't help that she hated Tate before the show started, but like the first episode when Tate first walked in the gym, Ronda immediately started throwing a fit. Tate wasn't originally supposed to be on the show and Ronda immediately assumed she was there to replace Ronda rather than the other coach, which was who she was replacing. She wouldn't even let Tate explain, just went nuclear on seeing her.