Rank system

It makes no sense, I started playing the game when summer sale began on steam and I got bronze 1 as rank after 10 matches (makes sense) me and my friend were playing RL for a few days and today we played another game, we got rekt 1-7 and decided to forfeit, But out of nowhere Both I and my friend promoted he to bronze 2 and I went to bronze 3 FROM 1 AFTER A FORFEIT. someone explain