After I Transmigrate Into a Book, the Side-Character Concubine Flees the Plotline

After transmigrating into a book, the doomed young lady has no choice but to stay away from the original story's imperial harem and cling to the heroine. She meets a young husband who is upright and rigid, but fun to tease now and then. They're childhood friends, after all. A quick-witted transmigrated side character heroine × a down-and-out top scholar who is serious to a fault