What a wonderful, tender, adult love story! You show us Millicent's self-doubts and her competences together (good mother, good worker, good friend, fearful lover), and by the actions and reactions of her daughter, her friends, her former enemies, and her lover how worthy she is of love and happiness and reassurance. She is strong, and has a good life, but it needs completion. Now she has it.
Then Viktor, the Quidditch star, enjoying Millicent, probably loving Millicent, but underneath the surface still young enough, insecure enough, to be put off by a hostile parent, and not to seek affirmation from the daughter. He knws better now – about loving her, about going after what he wants, but he's still in need, like Millicent, of being convinced he is loved and valued by his lover.
And your Frankie! A vital, strong character. And your depiction of all those Slytherins and Gryffindors, enemies once, friends who understand each other now, even though they all find sharp edges on each other often enough.