Is this a regular occuring thing for you guys? While I can see it perhaps happening once in a while, I'd not expect this to be the norm. There are a subset of people that think people are just here for their enjoyment/use, so that may explain some just abruptly dropping off. By the looks of your pics I'd say that's their loss for burning that bridge.
We tend to spend more time meeting people in person at parties than online, so we're probably less likely to experience this, or even care if it happened. It is very rare for us though. More often than not, life just gets in the way and we sort of drift apart, but we'd certainly not just ignore someone if they wanted to meet us or continue chatting.
We realize parties/events aren't for everyone, but the party/event approach is a lot less frustrating to meet and talk to people as well as schedule. For us, if we get to a point of clicking with and meeting people online, it's just icing on the cake.
From what I gather, those limiting themselves to online-only meetings tend to be frustrated with SLS. It has less to do with people being adults and more to do with some people just not giving a shit about others. Perhaps they did you a favor by ghosting you. It's worse being ghosted after actually meeting and playing with people IMHO.