The thing is, Kiba seems to be kinda stupid

ROFLOL!!!! I'm not making fun of your remark it just cracked me up when I read it!!! Kittens are like that...persistant, persistant, and persistant!!! They will work things out but I think maybe it is a good idea to seperate them now and then just to give Smitten a bit of a break. Make sure you give lots of love and understanding to Smitten and let her know that Kiba will grow up one day. Smitten just might miss her playful antics when she settles down.