Rude

I happen to think that it is very rude to cut off someone in the middle of a conversation, and just simply not listen or respond anymore. That has happened to me at least three times this week, and it is Tuesday! And, they were all entirely different situations, so it is not something that I am saying that is "causing" these actions. The first time, in fact someone asked me a question about what I thought on something, and as I was explaining it to them, they just stopped listening and reading something, and would not respond to anything that I said.
I dont understand how people can think that it is ok, I understand that people can be rude without realizing it, like calling after 10:30, or something like that, or interrupting, but just cutting a conversation off in the middle, how can you not realize that! What has the world come to?
OK, I will be done ranting now, and I will try not to rant on here again, I know that is not what you want to hear. Ill come back later when I am in a better mood.