Groves has been on record saying that he had abandoned him before the Froch 1 fight and he wasn't working with him enough - which he had done loads of times before. That is why he got in Paddy.
Adam Booth instigated everything. I'm sure Groves was warned about Booth & Haye being too-faced. My theory is someone told Booth that Groves had no chance of beating Froch cause the fight will be fixed & he (Booth) pulled a sly move to end the partnership.
It was over money and a investment gone wrong was the rumours. It was Groves biggest payday and i think Booth wanted a substantial increase and kind of scared/intimidated groves in accepting otherwise he lose. Groves didn't like it and left.
Can't blame Groves for that. If Adam was on a set percentage (that no doubt Adam himself set) why move the goal posts when George gets his biggest pay day? Adam, as much as I really rate him as a trainer, and really admire his smartness (he is very, very sharp and astute) greed seem's to get the better of him. Just be the trainer and let someone else do the managing.
FRom what I understand, Booth was on a % deal which is quiet normal but when Groves hit a big payday against FRoch he wanted it changed to a flat rate. Can see it from both sides.
There was a contract which stipulated 25%. That is the amount Booth successfully sued for not only for the Froch fight but also the remainder of his contract. Groves thought he could ditch him without paying but Booth took him to court. What the reason was for George leaving remains a mystery but it was said at the time he wasn't getting enough one on one training due to Booth training other fighters simultaneously (Andy Lee?) of course they are both fractious characters so it's possible they just had a disagreement. Booth had every right to enforce the remainder of his contract and George was obviously inexperienced and poorly advised regarding business side of things.