I'm not into teenage/innocent romance, most of my examples are more mature than the Itazura Na Kiss type.
Ab Ruk Online : Second couple. She pursues him and is jealous of another woman. She's a bit of a brat.
Rang Mai Hua Jai Derm : The FL. She's jealous and plots to make him fall in love with her.
Lost Romance : I didn't like this drama but many people do like it. The girl plots to make him fall in love, there's not much jealousy though.
Plerng Prang Tian : Second couple, the woman is super jealous and desperately in love. this is not cute at all, painful to watch.
Love lasts forever: FL confesses first and pursues him. A lot like Itazura but much better and healthier relationship.
My Sunshine