Be careful, here, because Roselily—presumably the woman who is getting married—is not actually the narrator of the story. The narrative is told from a third person limited omniscient point of view: the narrator is not a participant in the story's events (this explains the third person descriptor), and the narrator knows only Roselily's thoughts and feelings (this explains the limited omniscient). There is, obviously, an extreme focus on Roselily's feelings and thoughts during her marriage ceremony, which is what makes it seem as though she is narrating because we are brought so close to her emotionally; however, she is not.
In the ninth paragraph of Roselily's thoughts, it is revealed that Roselily is drawn to her future husband because "He sees her in a new way." Everyone else in her Christian community sees and judges her because she has had four children out of wedlock with at least two different fathers. This man, however, does not judge her for this, and she "is grateful" for it. She is curious about what "it will be like" not to have to go to work, not to work in a plant, not to worry about doing her job well. The prospect of not having to keep a job does seem to be appealing to her. He has "promis[ed] her [the] rest she had prayed for." This is certainly a part of her motivation to marry him; she is exhausted from working and raising her children alone.