In this oneshot, a mother's daughter has a reunion with her childhood friend, and the mother meets her for the first time in years. The mother notices that there is something special that she is noticing about her daughter's friend. This causes confusion, but she eventually figures out that she is in love with her. I think that she eventually mentions this to her, and the daughter's friend admits that she was in love with the mother. The story does not end with them getting together. It ends without saying what happens. Also, the mother had a special nickname for the daughter's friend when she was little. Finally, I think this was a Josei, although it might be Shoujo.
If it's the one I'm thinking of (forgot the name) then it has a sequel where the mom becomes a cheating whore who thinks she's hot shit for taking the girl her daughter likes while cheating on her husband, the daughter's friend becomes an asshole to the daughter because she's aware of her feelings.