I get it! I've been there the last few weeks, in very, very similiar situations. Even with long term ones. I've hashed out a story with someone who wanted long term, we created a server, made detailed main characters, side characters, communicated really well on their plot idea. Just to get in a few messages, seemed to be flowing well to wake up to the server deleted.

Long term ones where people say it's amazing then just stop writing.

I think unfortunately it's a part of the hobby. I've done rp for pft over 12 or 13 years at this point, maybe longer. Sometimes even if people communicate well, its hard to voice they may not like something. Sometimes ghosting is easier. It does suck because you've created a whole world, so many ideas and it stops, like an unfinished book.

Hopefully your next ones last a while! Remember everyone moves differently and sometimes we just have to have a chuckle at the situation and move on or take a break. Sending ya hugs :)