You need to take being a challenge clear into relationships. Slowly you ease out of it if its a LTR. Your not going to ask a girl to be yours and then instantly stop making her work for your attention.
Yes you need to make sure she knows shes yours but you still gotta make it fun for her. Sometimes when im kissing i will pull away and turn the TV on just to fvck with her mind and she loves it because she knows im joking but its still fun for her to try to get my attention back. Its that little challenge I give her everyonce in a while.
I could see in some LTRs where it would be ok to stop being a challenge eventually but for most relationships, expecially the high school ones, being a challenge is important, if not the key, to a succesful and healthy relationship.