They're looking at emails, texts, computer files, photos, GPS locations, bank accounts, call logs, calendars, website histories, Facebook accounts, you name it. There are now apps that can quietly track just about every aspect of your partner's life and give you any information you want at the touch of a button.
And apparently lots of people are doing just that. According to one technical surveillance firm, business is booming, especially among women trapped in abusive marriages who need to discredit their husbands in order to get a divorce.
Increasingly, people are no longer accepting what their partner tells them, or shrugging off the odd dubious explanation, but are bothered enough to find out just how truthful and trustworthy he or she actually is.
It must be dreadful when you lose trust in your partner and are sure they're hiding things they don't want you to know. But can you really justify such exhaustive snooping on everything they're doing? Is it necessary self-preservation or is it totally obnoxious?
Personally I've always trusted Jenny and I've never felt the need to spy on her every move. I often have no idea at all where she is but why should that make me suspicious? Why should I imagine she's secretly seducing someone or topping up a concealed bank account?
But the fact that such detailed surveillance is now so widespread and easy to use would make me think twice about bedding the next-door neighbour. If I knew that my supposedly private phone calls and texts could be instantly relayed to someone else, I think I'd keep my libidinous longings to myself.
