More than lovers, less then spouses - S1.E1

Machida Ritsuko and Nonoyama Shuichi (nickname Non-chan) are two thirtysomethings who have been living together for the past 8 years. One day, while Non-chan has gone fishing for the day, Ritsuko invited her good friend Niinuma Mina over to their apartment for some girls' talk. Mina then asked Ritsuko if she and Non-chan are planning to get married yet, to which Ritsuko replies, "He has yet to propose". At that exact moment, Non-chan was actually outside the door, having just returned from his fishing trip. Shocked to hear their conversation, Non-chan becomes moody, and thus begins to question their relationship. Although they have many things in common, but he feels they seem to be having many difference in opinions too...