Initially I was invited to farmville. I joined and played. I got hooked for a while. Then it got real boring and I wanted to quit but I still kept getting invites to stuff and I didn't wanna be rude to the person who invited me and gladly accepted. I am still getting invites which I'm still ignoring but it's painful.
Sounds like your being way too polite..
Just block the application and see if the person even notices ..