real friends

well recently i have had a few problems with my best guy friend, he's been my friend scince elementary school, this is our sophmore year in high school, and weve been hitting some problems. you can say that he left me for a girl, i know i sound so "omg, my boyfriend is cheating on me!" no he's just my friend but it hurts me to see that he dosent trust me and that that girl dosent like him, for sure dosent like him. HELP!!