Some people, on forums, seem to need to make a huge drama out of their comings and goings. Like there has to be this big fat ANNOUNCEMENT so everyone can speculate and dramatize and discuss and of course maybe a few beg you to change your mind. Big hoohaaa.
Just stop going. Then, in a few weeks/months/years when you change your mind and want to pop in, you don't have to go all the way back through the DRAMA of rejoining and explaining and apologizing.
Just fade away. If you have truly better things to do, you wouldn't even be troubled by it enough to ask.