In The Bear, Popova's and Smirnov's attitudes towards one another change over the course of the drama.
Both characters are distant when they first meet. Popova is in mourning. She has remained so for some time, refusing to even go outside in deference to her husband's memory. When Smirnov enters, Chekhov writes that he "speaks with respect" to her. He approaches Popova with courtesy when he says that he is "compelled" to call upon her because of a "very pressing affair." Their attitudes are distant because of their different priorities. He is concerned with collecting his money and she is focused on her mourning.
As they settle into familiarity, their attitudes change. Smirnov is convinced that his judgments of Popova are accurate. He questions the validity of her mourning because of her gender and believes that he has figured her out when no one else could. For her part, Popova cannot fathom that someone would disturb the intensity of her mourning with such rudeness. It is for this reason that she calls him a "boor," a coarse bear," and a "monster."
Their mutual acceptance of a duel confirms the intensity of their dislike. He believes that to "fight it out" with her is the only way to prove himself right and shed her label as a "poetic creature." Similarly, Popova feels intense joy at being able to "put a bullet" into Smirnov's "thick head." When Popova retrieves her dead husband's pistols, it is clear that the distant attitudes they once held towards one another have been replaced by shared disdain.
Their attitudes go through one more change in the drama's conclusion. Smirnov has become smitten with Popova: "I absolutely like her! Absolutely! Even though her cheeks are dimpled, I like her! I'm almost ready to let the debt go... and I'm not angry any longer.... Wonderful woman!" The intensity of their interactions has caused him to change his view: "God, what a woman! I've never in my life seen one like her! I'm lost! Done for! Fallen into a mousetrap, like a mouse!" His infatuation catches Popova by surprise. She is unable to quickly process the feelings he has for her, what she might hold towards him, and the mourning of her husband. However, it is clear that her feelings have changed when she shares in his kiss. Given the drama's one act, Popova's and Smirnov's attitudes have rapidly changed. From distant to antipathy to infatuation, Popova's and Smirnov's attitudes towards one another highlight the drama's comedic nature.