Okay, I'm going to give it to you blunt...not to be harsh, but this is my honest observation.
You asked for "another way of looking at it" and I think that's the issue here...you're not looking at it from the right viewpoint. For example (this is a biggie) what's the title of this thread? You're calling this a "relationship" and you haven't even been out on a date??? That indicates to me that you're putting way too much weight on this. It's just a girl...there's going to be many more chances with many more girls in the future.
And that brings me to my second point: you probably messed this up already past the point of no return. I don't want to be overly pessimistic, I'm sure you really like this girl and she's really cool and hot and everything...and who knows, maybe there's a chance. But you're treading water at this point, and rather than put all your effort into a losing proposition, why not just learn the lessons and move on. Personally, I don't think you can salvage this.
The main lessons I see here... Don't tell a girl to call you. You demonstrated to her that you lack leadership and initiative. By doing that, you put the ball in her court, and it's not her move, it's yours. You're saying "take the load of making a move off my shoulders, I don't want that responsibility because I'm too scared/a wussy/beta male/whatever".
So what's up with stopping after the first kiss and telling her you'll tell her the reason when she calls you?? Look at it from her point of view (which is always a "way of looking at it" that you should try to look at things).....doesn't that sound weird? Why DID you do that, anyway? If there was a good reason (and I can't imagine one) why didn't you just tell her right there?
If you really like a girl and want to pace the dating process out (instead of just get your nut off right away) then that's quite alright...I'm a big fan of leading things along at a slower pace. But there's a big difference between that and wussing out.
Maybe you didn't want to tell her your reason because you wanted to have some "Mystery" in order to entice her to call you. That's only going to work if you're projecting an image of decisiveness all throughout the interaction. If you're projecting a wussy attitude, it's not going to seem mysterious and enticing, it's going to seem like you're scared of something. Then you cement that feeling in her mind by saying "call me" instead of grabbing the ball and saying "I'm going to call you".
Good luck, man...hope that helps.