Why does it have to be this complicated?! Mao likes Itsuki, (maybe already love her?) but she is not sexually attracted to her, so how can it work, if they will stay together then she will get her sexual satisfaction from some guy, which is considered "cheating", it will not end in a healthy relationship. So I'm really not sure if Mao is really just a possessive friend since she didn't have a real friend before, so she want to monopolize Itsuki for her own selfish reason. (Seriously, Mao? You really want to stay like that forever? Girl, I'd suggest that you go to a therapist to clear up your feelings. I think you got some issues. Haha)
On the other hand, Itsuki is doing her best, to patiently wait for Mao with her childish, possessive attitude. I kind of feel sorry for Itsuki, I know that she's also doing her sly moves on Mao, but I don't know if she can win over this mind game, especially if her opponent is undecided and lax on some things. I'd say, Itsuki should go with the co-worker on a date, maybe it will broaden her perspective, or find a girl who will love her wholeheartedly, with no one sharing.
I'm sorry, I guess my comment ended up like a rant. How I wish the author will have another chapter to lock on the ending, so we'll know on which side it will fall.