My ex knew my passcode and I never deleted any messages, because I had nothing to hide. I suggested she put one on HER phone, but she said "I don't need one." A shady male acquaintance repeatedly texted her – she said he was planning a party. I was suspicious about his intentions. I checked her phone and found NO MESSAGES. ALL deleted. Naively, I mentioned this to her – within an hour, she suddenly had a passcode and would not give it to me. Less than a year later, I learned they were having an affair and filed for divorce.