would you know what she/he wants even if he/she is not telling you about it?

In a relationship, we have to listen to what is said but also look at the silent clues. For example, my husband loves games for his PS3; he says that he doesn't need anymore games, but whenever we shop together, he is always looking at games. Based on his behavior, I would infer that he would like a new game. Sometimes people say they don't want anything but yet they secretly expect us to surprise them. I think you should still buy a birthday gift (or whatever it is)for you partner. Just pay attention to his/her likes and come up with a nice surprise.