One time I read a seinen manga (seinen = "for grown-up men") with an office worker mc who hit it off with a comely lady and started going out with her. They went on dates and always ended the night having sex in a love hotel. One day she moved in with him. Their life became the life of a married couple; they naturally fell into the roles of working man and housewife. After a couple of years they started thinking about tying the knot for real, and had serious talks about what kind of wedding would be best. They even talked about children. Everything seemed to be going fine... when suddenly she went all moody and glum and sullen, and appeared to be irritated at him. He had no clue what was going on. Then one morning she faced him, hands on her hips, and demanded angrily that he say "I love you" to her! Yeah, because up to that point, according to her, he had never said those words! The guy paled, staggered back as if kicked in the gut, started sweating... and then claimed that it was WAY too early for that! His heart wasn't ready for something so big and she needed to give him more time. Like, a few more years!
The story, of course, was a parody. It poked fun at some classic problems of Japanese heterosexual couples—mainly at the inability of overly inhibited Japanese men to speak ther feelings. Ah, but, as we all know, all-girl couples are different! I really find it hilarious that the two ladies who make the main yuri couple in this manga have been living together, sharing a bed, having sex, and telling each other their passionate feelings of love and tenderness for fucking YEARS... and yet they still have never addressed the matter of whether they are gal pals, fling buddies, girlfriends, spouses, super friends, friends with benefits, just roommates, or what.