Why does my girlfriend say she needs space?

She wants to do other things besides be your girl friend.

She is confused if being with you outweighs her experiencing new and exciting things in her life. Just keep in mind that there is a good chance that you guys could break up, so be prepared for it.

Make sure to give her plenty of space, putting pressure on her will just make for a temporary band aids if it even fixes at all. Trust me... I just went through this just a month ago, and it did end up in a break up.

It's her girly kind of vague way of saying she wants out of the relationship.

It means she's pretty certain that she wants to break up with you,but by being vague about it she is(a) leaving you with some hope and (b)leaving the door open,should the 'finding herself'thing not work out.