My best friend is having a hard time because of me.what should i do?

too sad...im a girl, a 14y.o girl, i have a best friend..he's a boy.he's 1 of my clmates,i've seen his attitude either bad or good side(and he is just showing it only to me) and i can really prove it that he's really a good friend.although we just newly met,it only counts for 10 months maybe,but as days ,weeks, and months ped by, i observed that..there's no week we cant argue or quarrel,but my best friend told me, he really having a hard time because of me,so, what should i do?should i let him go? but we promised each other, "walang iwanan" (without leave), he's so kind ,and I can not let him alone.and i really trust him.and friends forever... what should i do?Do I need to fight for our relationship?im scared if he's expecting that we could be more than friends,because he's treating me like as more than bestfriend..and he told me that