You just know.
If you think she is cheating, she usually is cheating, almost certainly. Don't ignore your gut feeling, because its not a gut feeling... its one of your senses like feeling when someone is staring at you.
Like I said though, the most common types of wives I fukked were of wealthy husbands. These dudes would do shyt like have scheduled trips out of town to where their wife could hit me like a week in advance and make plans. I never understood doing some shyt like that. If you own a nice ass car and you leave that shyt parked in the same spot for three days straight don't be mad if you come back and somebody broke into your shyt, thats all I'm saying.
The other thing I would say is if you are letting your wife or girl go 'clubbing' you are definately fukking up, but especially if she is specifically going to see a band she is a fan of. Its probably better to let them go to a male strip club in my opinion than to let them go to a club at all. The likelyhood of them getting fukked at a male strip club is much much lower. If you understood how hip hop tours went down you'd be on legalzoom looking up divorce right now.