When people have mutual friendship, they can send an couple registration. [there isn't cost, this will be free!]
when people become a couple, they will be able to level up playing together, obviously you start from level 0, the longer play together, but will gain levels.
yet give me an idea of how serious both profile and basic information [as the info that is displayed while playing]
osu! obviously does not have 3d avatars, so obviously not be able to make a dance couple, but a battle of couples ... where the winner takes the loser point. [say, I have my couple, and 1 couple have 600 points, and the other couple is 580, if the couple defeat rival couple, then you would win a certain amount of points playing certain level [almost like PP]
I'm still thinking of more ways for couples, but for now I suggest to have the opportunity to become a couple.
''please sorry about my english, is so bad''