In She Stoops to Conquer, the relationship between Hasting and Constance is traditional in contrast to the relationship between Kate and Marlowe. Prove it.
Kate represents a reversal of sex roles, as it is she who pursues Marlowe; and this relationship is juxtaposed by the more traditional relationship between Hasting and Constance.
Hastings and Marlow in this play are very different, as it becomes clear. Hastings is able to converse smoothly with the opposite sex, whereas Marlow becomes quickly tongue-tied and is unable to speak using the various flatteries and rhetorical strategies that Hastings uses to win the hand of Constance. Note what Kate concludes at the end of their first meeting together:
Was there ever such a sober sentimental interview? I'm certain he scarce looked in my face the whole time. Yet the follow, but for his unaccountable bashfulness, is pretty well, too. He has good sense, but then so buried in his fears, that it fatigues one more than ignorance. If I could teach him a little confidence, it would be doing somebody that I know of a piece of service.
This is when Kate first begins to dream up her idea of reversing the sex roles and actively pursuing Marlow because of his "bashfulness" that leaves him unable to fulfill the normal male role of pursuer. Note how Marlow himself describes his inability to talk with the opposite sex:
I'm doomed to adore the sex, and yet to converse with the only part of it I despise. This stammer in my address, and this awkward unpreposessing visage of mine, can never permit me to soar above the reach of a milliner's apprentice, or one of the duchesses of Drury Lane.
What necessitates the reversal of the sex roles then in this play is the inability of Marlow to fulfil the normal role of pursuer that was ascribed to men. Constance is able to let Hastings pursue her, because he is able to express himself well. Kate, on the other hand, quickly realises that if she wants anything to happen, she will have to be the initiator and the one who manipulates the situation to bring them together.