I don't think it was that she was being "abnormal" as in illogical, she was being abnormal as in trying extremely hard. She obviously had some pretty ugly experiences before him and was so determined to work things out with him even though their personalities mis-matched, that her effort came out as forced and tiring. It's like trying to keep up with a friendship because you really like the other person but the two of you always have misunderstandings. At some point, both sides are too tired of explaining and discussing and clearing things up, and just drift apart. The moment you begin forcing yourself to do smth, it's not smth you enjoy anymore. She was like that right off the bat, get it? The no ashtray thing was just the perfect example of it and I guess made everything really obvious. And awkward.
She made it look like he was abusing her in front of his students.
She embarrassed him when she came off as an abused wife in front of his former students. She also couldn't accept him for the kind hearted person he is. She kept expecting him to treat her poorly.
hm... i dont understand with the old man and the wife-sachiko story.... I mean, what's wrong with the no-ashtray-problem? The old man forgot he never smokes in the house so the house doesnt has any ashtray. Then, sachiko offered a tissue/handkerchief(?) so that the ash wont make a mess...... and....? what's wrong with that? what's the shocking look on everyone's face for? i dont get it. Can anyone help explain?