I have seen few of such examples (the example you gave about the wife who begs her husband to marry another and then she is treated like dirt, but still continues to be very nice) in real life. Nothing (overly) unrealistic about it.
As for the evil ones being heartless and the good ones being very sweet and too kind, i have seen those people too. In my direct family.
Nothing exaggaretd about that as well.
The only difference between a drama and real life is, that in dramas there is often a good ending. And in real life, the misery often continues. Unfortunately.