I wonder if "The Gift of the Magi" by O. Henry might be a possibility. In each of the stories, the reader is presented with a kind of snapshot of a married couple and in each of the stories, there is a surprise ending that reveals to the reader the state of the marriage. As for differences, one marriage is so dreadful that the idea of continuing it actually kills the wife, and in the other, the marriage is revealed to be so strong that the husband and wife willingly give up their most precious possessions for the other.
I do not know whether your assignment permits you to go beyond the texts, to examine the era and or the authors, and this is something that you might want to clarify with your teacher. The publication dates of the stories are only eight years apart, written in the same era, but they are such completely different takes on marriage. Something to think about is whether or not a male of that era, O. Henry, in this instance, had a more positive view of marriage than a female of the era, that female being, of course, Kate Chopin, who wrote frequently on the struggles of women.
This might be a stretch. Yet, I think it would be really interesting to contrast Louise Mallard from Chopin's work with Connie from Joyce Carol Oates "Where Are You Going? Where Have You Been?" Both characters are women who struggle with voicing their identity in a social setting. Yet, both experience this in different ways. In the end, their end fate is similar in that both of them die, in large part, due to the patriarchal surroundings in which they are immersed. It might be interesting to find some similarities between both female protagonists even thought both of them are vastly different. Connie is, for all practical purposes, a modern teen, much more socially aware and savvy of her condition in the world. She is seeking to be in control of her own identity, something that is fundamentally challenged when she meets Arnold Friend. Louise is a housewife who has spent years being silenced. Yet, the moment of her husband's death brings an awakening of sorts about the potential of being able to control her own identity. Both characters are able to touch, if only for a moment, a realm where they are empowered and are in control of who they are and how others see them. Yet, this is temporary, a fleeting state, as the end of both stories undercut a moment of triumph and turn it into brutal defeat. Contrasting both visions of femininity might be very interesting to see from a women's studies' point of view.