I'm pretty sure a few people have done that with me simply because I'm never on Facebook. On the other hand, if that's the only source of contact and the response to that realization is to terminate it as well, perhaps that, too, is for the best. Some folks don't like being reminded that friendship is more than clicking "like" on a status update every few weeks (which is also for the best, since I'm not on Facebook enough to do that. )