Why My Friend Hates Me?

Hello im a 9 year old girl . In Second grade my friend kyla came to school i gave her a guild/tour in the school then later we become best friends then after 1 month she ditches me for the popular gang in the cl she try's to put me in the popular gang for 2 days then after 3 days she forgets about me when i try to talk to her in second grade she pushes me away . Now were in third grade and in the begining of the year we are best friends then after 4 months she ditches me for her crush David even tho me and he are best friends and today when i asked her to be my partner first and my friend david askes her to be her partner she goes with him even tho im her best friend and now navi who hates me since first grade takes over me . All i want to tell my friend kyla is ''Why you always picking the cool gang people just pick the smart dorky group'' so please help me out and do something