I think that having your own life IS important, but "being hard to get" sounds like you are making your gf/bf have to justify why you should take time out of your already established [read: more important] schedule/life to be with them. That is wrong. If someone is important to you you'll make time for them. As you pointed out that doesn't mean pining over the phone awaiting their call and ready to go out with them at the drop of a hat though. I just think that "being hard to get" is not the right way to explain it. Self respect, boundaries, and self reliance would better sum up what you're saying in my opinion, also keeping in mind that if the other person is important to you that you'll make time for them though.
...one can be sure of nothing until it has already happened...