Topics like this don't really lead to valuable discussion and often turn out negative. Sorry to hear you're thinking about leaving us.
Personally, instead of making a big deal out of leaving a forum I just log out for the night and if I never feel the urge to log back in again the next day I just... don't. Leaving doesn't need to be a big decision. If you feel like logging in that day, great. If you don't, just don't. It's as simple as that.