Just thought I'd chime in here..

It's not possible to get every single girl. Sometimes you might do absolutely everything perfectly but still fail. There's so many variable circumstances to take into account that are well beyond your control. You don't know what's going on in her life etc etc. Alternatively there may simply be a genetic reason for it, we are predisposed to seek those of diverse genes to our own, this can cause a lack of attraction in even the most perfectly compatible physically/emotionally/socially.

Even when you're on top of the world, feeling great, being awesome, doing everything right, you can still lose out. If you can't see an error then very often there isn't one.

As an alternative possibility, it may be that she lost interest after the kiss close because the excitement disappeared for her, she has you and knows she can have you now having achieved that goal. You need to get her to continue chasing your attention by creating excitement and not seeming like you want her all that much.