Kazu mean if Kidaka have said they have to break up and going "friends" again, that time Kazu will not tolerate and leave their house.
Thats right..
This manga remind me the one of bruno mars song,.." When i was your man"
I thought it was Kidaka who said it... He felt Kazu staring at him and knew that Kazu was wondering what if it happens again or something.. and then Kidaka called Kazu dummy and reassured him that there won't be a second time where he will break up with Kazu. Kazu's face looked relieved at the end... and said that the nightmare is over.
What did that last line mean? There won't be a second time? Will Kazu leave Kidaka now?