The question is too: "when does cheating begin?" It begins way before the hotel room door- it begins with an 'innocent' conversation, some harmless flirting, or a guy white-knighting a friend-in-need a little too much. I believe, that if I can't open my whole life, my secret thoughts (and my phone), to my partner at any time, then I'm hiding something. ( I was, when I was being a shitty cheater.)

I think it's not to ensure good behaviour, even in a healthy relationship, and it isn't spying. It's trying to be as open as possible with our loved ones to ensure that someone is not going over the edge 'by mistake', you know... "oh, this friendship with Jane, it's nothing really, she needs some help with her renovations... went kinda late again... yeah we had a few drinks..."

Affair help-forums are full of people who get into affairs 'by mistake', they didn't see it coming, they didn't mean to... I spend my time now trying to see the ways I got myself into trouble by be willing to hide stuff, conversations, people.

Could you hand over your phone and all passcodes to your partner right now, this second, and feel comfortable that there isn't one dangerous secret stashed somewhere in your phone? We don't really want to know, it's a rhetorical question. If you have no dangerous secret hiding anywhere on your phone, that means you are likely a person of integrity and congratulations are in order!