This is a novella, and because it is not a full-length novel, some missing elements can be forgiven. We are basically treated to a glimpse into the lives of Sophie and Carter at a turning point, like looking into a window and watching a scene play out. We don't know all the details, such as how is Carter able to support himself and his mother financially without a job and still help Sophie out with groceries once in a while? We know just enough through recalled memories on both their parts to piece together the big picture.
The family lives of Sophie and Carter are nightmares that no child should have to live through. It is extremely heartbreaking to see the abuse even through their memories. The neat and tidy ending that allows them to be together gives us the HEA (to the extent that is plausible for them) that we feel they deserve.