Hmm, I don't even know what to think here, lol.
I remember when I heard William was joining the army, I thought it's gonna be hard for him to be apart from Kate for so long (since reports suggested they'd been spending a lot of time together).
Then on top of that heartache, they both had to deal with all the press following them (especially her) around and the rumors about a pending marriage that may or may not have had any basis at all.
I think maybe they both needed to figure things out (I could imagine under those circumstances, having the need to figure it all out - after all sometimes these types of situations can get out of control and can cause people to wonder if the reason they're still in it is because they love each other or for something else).
They probably both just wanted some time to work out their own issues, whether together or not.
Somehow or the other though, whether or not they do get back together, I suspect there will always be people (and the media) spreading rumors that they are back together and that they're going to get married. Which (if they're lucky) will probably only stop upon William's marriage to someone else.