Everyone is "lesbian" for Takahashi as far as I see it.

But anyway, as for MoMusu...
Risa is her closest friend, naturally. 5 years of friendship. I know she gets along with Miki, since they used to be regulars on Young Town, and they've made appearances on shows together. Sayumi has been her "little sister" for a good while. And lately I've noticed she's been with Kame a lot - latest spotting during the Volleyball games. Also, futarigoto.
And of course, the infamous Rika-dono/Ai-dono pairing.