Her argument was, since Brigid and Cayden were not dating, it was not cheating, regardless of Brigid's feelings towards Cayden. She further argued, even if Korra had full knowledge and wasn't a dunce (Afterwards I did tell her she was an alien and she retracted that) since Cayden had no idea about Brigid's feelings, she had no right to be mad at him, but solely Korra. At one point early on in, she did blame it all on Brigid since she went to Mikhail and Sasha first instead of Cayden, but after I explained who they were she was like, 'Oh... well now I feel dicky.'Well, if Brigid had stated how she felt clearly to Korra then I would strongly disagree with that. Because at that point, sure, Korra could still go after Cayden, but at that point she'd have no right to call Brigid her friend if she knowingly slept with someone that Brigid was interested in.
Ah... good times.
Though when I also told her about Kallpa, her quote was basically, 'Well, shit... Cayden is fucked.'