Things that make you go HUMMMMM

As I write this, I wonder how many times I have tried to touch someone by leaving a note on the bio or drop a short message. Many accept my invitation for friends, but never hear from them again, or the others? We write, converse, and after a few days....they are gone, never to be heard from again....
doesn't that ask the question? WTF
why?
don't you get PO'd when guys do that to you, but it's okay for ladies just to drop off without even saying FU before they go.
Let me know what you think?