Random Add, Then Ghosting??

I get ghosted a lot. People will send me stuff and I’ll respond, but they never respond back. A couple of weeks ago, an old friend from when I was little accepted a FB friend request I sent out MONTHS ago. She asked me about my life and I answered, followed with questions about hers. No response. She saw my message and left me on read. Has this happened to anyone or does anyone have an idea why this is such a common thing nowadays? It’s incredibly rude and also confusing and kind of sad.