I'm pretty sure Deadmau5 cheated on Kat Von D. The way Kat broke everything off so quickly yesterday and how she said it was a no brainer and the way Deadmau5 says that he is not ready for a relationship would lead a reasonable person to conclude that Deadmau5 cheated. Either that or he told Kat that he really hates tattoos and that all of his are temporary that he keeps reapplying just to look cool and because he wanted to have sex with her. I admit that could be a possibility too, and honestly, the much more fun one because some guy cheating on some woman happens a million times a day, but to go to the trouble of getting a bunch of temporary tattoos and to keep reapplying them? That is dedication. You don't find that kind of dedication outside a Lindsay Lohan pickpocket class.
Source:
http://www.crazydaysandnights.net/2012/11/kat-von-d-and-deadmau5-split.html