So chapter 5-6 she says she has to tell her sister-in-law that her husband's body has been found, which means her husband is confirmed dead, which is why her brother is trying to set her up with another marriage, and meanwhile she's hoping her low status means no one's paying attention to her actual status so she can lie that her husband isn't dead to keep some distance with this Walford dude.
I'm not really sure why the brother wants to set up the marriage...? Does he get an introduction fee or something?
(I'm just gonna ignore that she's keeping her distance from Walford bc I'm pretty sure that's some sort of plot armour that keeps him intrigued or something)