Since she wasn't going to get to perform the closing stage at A-nation, she wasn't going to perform at all. That's a bit diva-ish if you ask me. I've got nothing against her because as said before, she is an amazing artist, just not the type of person I personally like. With music though, it doesn't matter as long as they are a good artists, which Ayumi is.
& it was confirmed somewhere that she did in fact cheat on him ; but you're all right. it's not our business & we should stay out of it, but my ignorant feeling-charged opinions do get in the way sometimes.
http://choscandalo.us/tagged/Ayumi-Hamasaki