Frustrated? Annoyed? Confused? Maybe all of them.
I simply cannot understand why one can be very mysterious about their relationship with another person. It just irks me. I really don't see what the benefits they get when doing so. Of course, I am not asking one to publicly announce the news. But when asked, just give the truth. It will not kill anyone.
Some of them claim that they do not want to make a big hoo haa about the matter (Nobody asked you to, anyways.). Some are afraid that they might complicate things if the whole world knows about it (It's already complex to start off with, anyways.) And the list goes on and on.
You can be Brad Pitt and Angelina Jolie or Britney Spears and Fred Durst, for all I care. If you are seeing someone in question (and you're been asked about it), just admit it. Sooner or later, the whole world is going to know about it, anyways. So what difference does it make?