Locks his cell phone/computer/car. Takes his phone into the shower with them and you can't look at it. Does not take you out to dinner or out on the town or does not want you to hang out with his friends...being alone a lot more than usual. Those can be signs that someone is cheating.
Hi Diamond! If that's happein to you girl, that sucks and I'm sorry. Look thru his wallet. Not just for receipts or numbers, but for cash. Most people in a serious relationship know what the other person makes and has to pay, so of you see a quick drop in funds and it's consistent that may be a sign. Look in his car, the adjustment of the passenger seat. The normal stuff too- Facebook, email, text investigation. And check his homies too, when there's one cheater there's a "mentor" to help him. Good luck darling!