Why does it automatically have to mean cheating?
What if it's a betrayal of trust? What if Aaron confides in Robert about the struggle he's having in prison? The marijuana use? The bullying? The beating? One of the articles say that he's not sure if he should tell the people he loves. What if Aaron confides in Robert about what's happening to him, but he makes Robert promise NOT to tell Chas. However, maybe Robert is "tempted to betray" Aaron's confidence by telling Chas what's happened to him because he doesn't know what to do or how to help Aaron from the outside.
The reason this came to me, was because I remember back during the abuse SL, Robert didn't want to tell Chas about Gordon. They were in Vadam's house and he told Chas "I'm already betraying his trust" in regards to him saying too much.
So...as I've said before, I have 200% faith in Robert and his fidelity, so I offer an idea as to what the spoiler may actually mean. Thanks for reading!