I see a lot of comments that show people are really misinformed when it comes to poker, and don't understand the specific play that resulted in Garrett calling his opponent a cheater.
Let me start by observing I don't know whether or not Robbi cheated. I don't think the evidence is that strong, but it isn't exactly weak either.
Robbi's call made no sense at all. When Garrett shoved all in with low equity (a bluff), the play makes sense because of what is called 'fold equity'. If you think your opponent's hand is weak, it makes sense to bluff because they'll be forced to fold. Plus you have to bluff at reasonable frequencies, or nobody will call you when you go all-in.
Robbi on the other hand was not bluffing, she was calling an 'all-in'. The problem Robbi has is that as soon as she calls, it goes to showdown. There is no fold equity available to her. Not only was her hand terrible, it had almost no prospects of improvement.
Further, even IF she somehow KNEW that Garrett was bluffing, she can STILL lose the hand a million different ways, even to his bluffs. She had Jack-high!
So the folks suggesting that what she did was reasonable are insane. There is no world in which anyone who knows anything about poker calls that hand - absolutely none. The only real possibilities here are that she made a mistake and got lucky, or she was cheating.
The other thing to know is that the evidence consists of more than the fact that Garrett lost the hand in a strange way. Robbi's explanations after the hand made no sense either, and there was activity at the table that was suspicious. Her buy-in was suspicious as well. It's also extremely weird that somebody with such limited poker experience would be playing at these stakes, and somebody else posted her buy-in. The person that posted the buy-in was another player at the table, adding to the suspicions.
Garrett has a well-deserved reputation (at least, had) for being a gentleman at the table, and never losing his temper or reacting poorly, even when his opponents did shitty things to him. For him to go as far as to lodge a cheating allegation was pretty crazy.
To emphasize, I don't know that Robbi was cheating, but if you aren't at least fairly suspicious, you haven't been paying attention.