If you've ever been in a relationship where you suspect your partner is cheating, finding proof of infidelity becomes an obsession. You start questioning every outing they make. And if they happen to smile while they're looking at their phone, that becomes a major red flag.
The worst part is that even if you manage to snoop through their device and find nothing, your fears aren't exactly quelled. That's because you may suspect that they've just deleted whatever implicating correspondence you were expecting to find.