Hahah, yeah I think this is kind of obvious for some outsider, but I actually have never had other account on the PC. It would be very weird to create one now and she would be very suspicious. She has this weird thing that turns my need of privacy into something potentially bad. For example, the facebook account: I don't have the habit of logging off from it, so it is open every moment even when she is using the computer. Sometimes she sees my messages, and really, I don't have a problem at all with that. The problem is, sometimes you need your privacy, and because of our very intimate relationship, she instantly thinks I'm doing something bad/wrong. Maybe it is kind of my fault because I give her too much freedom, but then again, she is like my best friend and I don't want to lose that. So yeah... I don't know. I'm still 18 years old though. She is still realizing I'm growing up I guess, hahah.
Is she very computer savy? Are you on Windows?
1. Put the game in a folder
2. Rename folder to something innocuous like "Winsys-2201x"
3. There is a Windows function to hide this folder so use that
5. Scrub the files from your downloads
4. ???
5. profit
I haven't used a Windows PC in a very long time but this always worked for me.