Ok here is the most common Mac logger programs.
http://keystroke-loggers.staticusers.net/mac.shtml
Best bet it to first figure out what program is being used then one can figure out what to do to disable it. As for trust well just shows you nothing you do at any computer is private and if anything can be used against someone it will be if it enables the other person the upper hand. Maybe the friend cannot afford the marrage, sounds like a classic power and control issue. Have any of the talk shows done this subject LMAO would be better then trailer park antics...Opera, Jerry, Maury, Jenny, Jerry LOL where are you?