Reminds me of a guy who planted loads of spyware in his girlfriend phone. He genuinely said it killed all doubts and made him happy and ensure he could make her happy.
A female friend of mine had such a bf. We figured it would be fun to put a location randomizer on her phone and pretend not to know anything about her daily foreign trips. His spyware certainly didn't give him a whole lot of confidence but he was at the same time loathe to confess he knew where he thought she'd been.
Assuming he was indeed truthful saying that, I doubt that happens in most such cases. I think the type of people who do that also tend to "overreact" over anything their partners would do that isn't 100% in concordance to what they said they'd do, which I think in the end leads with a breakup or a bad relationship/many fights, etc.
