3. Your partner becomes super protective of their phone
The very aspect that makes cell phones so great is also one of their points of detraction: the ease with which people can communicate. They’re great for keeping us connected to our friends and loved ones, but they also make it a lot easier to cheat.
However, there are certain phone behaviors you may pick up on that can help you uncover an affair. For example, leaving their cell phone in their car when you’re together. According to Dr. Tracey Phillips, a counselor and therapist, "[t]hey could be trying to avoid receiving any questionable calls or texts in your presence," so take notice if they suddenly make a new home for their cell in the car.
Suddenly changing their password to one you don’t know or simply making their phone off limits to you is another sign of potential infidelity. They obviously don’t want you to look through their phone because they have something to hide, and more often than not, it’s their cheating.