I'm going to be real honest here, people change. I've had a friendship that went on for 8 years and we eventually parted ways. It happens. That's just how life works and not every friendship will stay within that "honeymoon" phase, sometimes they get serious, sometimes they break off. If you and your friend keep getting mad at each other for no aparent reason, maybe they're hiding something from you. Either way, I'd say you ask what their deal is and all else fails, part.
Sometimes this can happen between friends.. it's happened to me lots of times.. just give it time, otherwise you can just straight up ask her why she's been so distance lately.
*Distant
So.... I've been best friends with this girl for almost 2 years now but something changed the last couple of weeks and we keep getting mad at each other and she is distancing herself from me...i dont wanna lose my friend and i want things to be the way they were before but nothing seems to change even when we say "oh lets try again maybe we will be like before"...i dont know what to do. Please help. ╥﹏╥