Manners?

It occurs to me that either I attract people to me that are socially rude jerks or that society just doesn't care about manners anymore and I do. For instance I decided to have a get together at the local bowling spot. I invited everyone in advance and then waited for reply's. Everyone but one person let me know. I asked said person again, stating that I had to know in order to book the appropriate number of lanes. No response. So I went ahead and booked counting that person out. Now could someone explain to me that person's thinking? If you aren't going to go somewhere just say so. For heaven sake's am I going to beat you with a stick or something because you won't go to my function? Then I had another incident where I asked an acquaintance for coffee. I said when I was available and left it with them. Never heard back, not even to say "can't make it " Just nothing. I never know what to think about these situations because I am so good at trying to see everyone's point of view and making excuses for people. Well maybe they forgot, (not) or maybe they didn't know how to say no (just say you can't make it) Are these people completely dissing me and therefore I should cut them from my life? Or is it now socially acceptable and common place to be rude? I know that deep down I feel these people do not have enough respect or common courtesythat I will think twice about putting myself out there again. I am far from perfect but I do reply to invites and if I forget I apologize!