I have this happened to me here and also in other forums that have the same option. It sucks when it happens. It reminds me of ghosting a lot.
I hate when people do that. It's like that they are Imature and uncapable of communicating. How hard is to admit to someone that you don't want to roleplay with them anymore? I bet in real life all these people who do that actually bunch of cowards that avoid facing the situation when they have to cut off people from their lives face to face. I bet they do it by texting or just ghost them.
I have the bad experience of having people totally ignoring me during the OOC plotting without explaination, like for no reason. I message them more than once wanting to know if they are still interested, and yet still Ignore me. Like not even leaving the conversation. And yet, I see them online. This happens to me in pretty much every roleplay forum that I am member of...
Sometimes I'm really considering giving up on roleplaying...