@JoJose The problem is that sensei is bored to death, her husband leaves her in a shabby apartment and works on the road most of the time...moreover he is rigid, doesn't particularly like sex...
Just the opposite of sensei, who from a very young age has had an aversion to perverse borderline sex... she also has a huge weakness for aki, and always on the red line.
We can see that for the scenario the author is obliged to let her get married, otherwise it would mean that nothing would stop her from getting married to aki.
It would have been nice if she had admitted that playing the model wife at home while her husband works does not correspond to her.
In any case, even if they were no longer Neighbors due to the collapse of a building, it wouldn't prevent the boring routine of sensei's marriage from causing one and only one thing: divorce.