I feel that most people are a bit harsh on Nico here.
It's a lovers quarrel, and knowing both Nico and Maki of course they will exchange more blows than the others couples. Particularly when Nico show off her childish side.
Seems that was a special ocassion, with Nico cooking and all. Of course, surely Maki had an emergency or something and surely can't be helped. But, Nico being Nico of course will get angry. And Maki being Maki... well, it's easy to picture the whole thing.
One is angry at something that she put a lot of love and effort to be wasted, the other is angry for being blamed for something that she has not power to change. (And surely also for not being able to eath Nico cooking and having a romantic dinner).
Or also can be that Nico was cooking and they had a fight. Then Maki leave the house, went to drow her sorrows with some drinks, leaving Nico alone with the food that she prepared with all her love and effort.
Nico has to eat alone, and her wife doesn't even respond her calls.
Of course, knowing Nico, probably the fight was her fault, being a bit childish and explosive, but...
Whatever case could be, I don't think that Nico is being particularly manipulative... is just that both of them have a similar personality, at least in some aspects... and of course that will make them clash. Sometimes hard.
But their love is stronger!!
And of course, maybe I'm wrong in everything and the story is about something else...
Anyways I forgot to mention that I loved the Bird-Kotori "FAITO DAYO!"
PS: English is hard... I'm in despair after writting all that.