With this Kiss: The Complete Collection [Eloisa James]
This novella spans more time then I expected it to. Both Grace and Colin are children when the story first starts, but it gives us a glimpse of their relationship before the idea of romance and love started. Colin acts like a fool then realizes it. It would have been his own fault if he'd really been too late. There isn't a whole lot of drama, but Grace, after Colin sees Lily at the ballroom and gets lost to her, was heartbreaking.
I'm kind of wondering now if Lily and John are going to get their own books. I'm tempted to say yes, but the end of this novella is 9-10 years (at least) in the future, so the author would have to back track for that to work. Not really an issue, but having the epilogue in a child's POV suggests this being all we get for this timeframe. I could be wrong. I don't think Lily is mentioned at all, although Colin and Grace's children have cousins that doesn't mean they are Lily's children since both Colin and Grace have siblings.