I feel about the same way as you guys.
She/he is going to do it anyway, internet or no internet. If you don't have trust, you have NOTHING. Tammy knows if I screw up (not happening) or she just doesn't want to be here anymore, she is perfectly welcome to walk out the front door with no hard feelings. I will miss her dearly and probably love her forever anyway, but there is no reason to cheat. If you/they are not happy, then leave.
If your spouse goes out sometimes with his/her friends and doesn't come home, you should feel rock solid confident that they are sleeping on a buddy's couch and not shacked up somewhere and that they will call you as soon as they wake their drunk *** up. No, I havn't done this (have I?) but if I did my wife/me would be ok with it occasionally. We have only had one fight, ever, years ago and neither one of us even cares what it was about.
You just don't say mean words or things to someone you love and we never piss each other off on purpose.
I know this is rare, but I feel that if your spouse is not your best friend and you don't have this kind of love and trust in your relationship you're wasting your time. Is restricting her movements or making her stay at home, no facebook, no myspace etc. really going to make her love you more? I don't think so.
Just my humble opinion.