I am increasingly finally hearing a word for the phenomena that has existed online since I started using tinernet in 1994: "ghosting." This is where you enthusiastically communicate with somebody online (it used to be IRC or various chat services, now its mostly social media) then quite suddenly they disappear. You are unfollowed, defriended, maybe blocked, phone calls unanswered (or changing numbers). The person literally "disappears". Congratulations, you've been "ghosted."
That said, with an increasing number of people multi-purposing their social media accounts for business purposes, boundaries often get blurred. A few incidents highlight the problem of using social media for many different purposes, and especially using the same account. One acquaintance, a slightly controversial writer and relative of somebody who has recently been subjected to some of the worst online abuse I've ever seen, disappeared off social media for quite some time after finally giving up on the snideness. Since we'd never actually met, I didn't have a direct contact, though I'm still in touch with her amazingly resilient relation. Though not true "ghosting" as the Americans call it, her disappearance left a gap in the lives she touched online. I was delighted when she eventually appeared again, it showed that it is actually possible to miss folk whose presence in your life is largely or entirely mediated by technology.
Another friend, whom I have had the odd pint in London when over, has been through a few dreadful years over an online abuse case she lost, which though not as obvious as the cases of some of the other celebrity abusers, makes you wonder who was really wronged. Either way, the interpretation of the law in England comes down viciously on the side of the accusers, and appears to disregard physical distance when considering online abuse. This has created a dangerous precedent of many folk being charged for making threats verbally in online recorded forms, or even, in the case of my friend, repeatedly referencing somebody who didn't want to hear from her and equating it with physical stalking. This has created a dangerously manipulable online ecology where abuse is in the eye of the beholder: powerful interests can seek to silence criticisms as "abusive" through accusations of online abuse. The impact on her life has been truly dreadful, far worse than somebody criticising a book or theory could ever be.
Then I was rather saddened to find that a couple of folk I regarded as distant friends, but friends nonetheless, having met a couple of times, just randomly defriended me, leaving an awkward trail of connections through other services, which was actually quite difficult to know what to do about. There is a certain etiquette about social media defriending I find, that depends on really what the offline nature is. If its somebody you've never met in your life, and to whom there is no real connection, well then its fine to disconnect, but selectively doing so on just one service while leaving them connected on others? The message this sends is ill-considered, to say the least, and probably says much more about those carrying out the actions. So you took the trouble to drag through your friend list and "punish" your acquaintance by defriending? But you think you are still being "nice" by neither blocking them, and staying connected elsewhere? Or is that simply a provocation to "prove" how dreadful they are by hoping they'll retaliate by blocking you? Or have you not really thought it through, and just forgotten? Given that social media is, well, social - couldn't you just, well, talk?