Nope, I'd consider that rude actually.
I have sort of just stopped talking to one guy though, it was back when I was 19 and I was terrified to break up properly because I didn't want to hurt his feelings.
He was a sweet guy, but we weren't looking for the same things.
He wanted marriage+babies+making me move away from my mom, and at the time that scared the heck out of me. (to be fair, he was talking about all that by our third date though, and the 17 year age difference didn't help either)
I still feel a little bad for just disappearing without a trace on him though. x_x