I dunno about victim blaming, but if someone is cheating then the relationship was already dead. One or both people might be in denial about it, they might be refusing to admit it because kids/house/family ties. Or just guilt, social circles, or a genuine desire to not hurt the other person. Cheating is, among a long list of bad things, one person giving you the ultimate notice that they want to break up even if they don't admit it.
I don't think I'd ever blame someone for getting cheated on, but I do kinda scratch my head at people who act shocked or don't see it coming. How can you not be aware of a relationship dying while you're in it?