Mia and Mo meet in Episode 1 and became good friends.
Both had a visible crush on each other; Mo've been charmed by a new girl, to Yuko's dissaprovement, and Mia actually liked Mo too. No matter how it ended, Mia and Yuko never had serious fights because of Mo, all three of them are good friends, loyal to each other.
In the second series it seems that both Mo and Mia lost romantic interest in each other, still being really good friends. BY THE WAY WHAT IN GODS NAME IS MOE WEARING HUH IT MAKES NO SENSE IT IS SO UGLY AN UNPRACTICAL THAT IT LOOKS LIKE A 4 YEAR OLD WHO HAS NEVER SEEN A MALE IN THEIR ENTIRE LIFE COULD HAVE DESIGNED IT