Or: Five things Sally Hope can never tell Darrell Rivers
The main reason Sally was so angry at Darrell that first term at Malory Towers was because she kept talking about her little sister Felicity. Darrell loved Felicity, and missed Felicity, and wanted to share the joy of Malory Towers with little Felicity. And every time she Darrell mentioned Felicity, Sally thought of the hated Daffy, who was taking up all her own mother's time, and was the reason she'd been sent away.
After Sally missed the first half of the first term of Third Year, she came back to school to find her Darrell arm-in-arm with Alicia Johns. By then Sally knew how to recognise her own feelings of envy, but it didn't lessen the pain. She wanted to fight Alicia for Darrell, would have been willing to scrap it out on the beach somewhere, up to and including hair pulling and face scratching. She wasn't proud of it.
Sally wanted to apply to Cambridge; to Girton or Magdalene. She gave up on that dream because Darrell was single-minded about St Andrews, despite the fact that it was at the opposite end of the country, far, far away from their family and friends.
Sally submitted her application to St Andrews along with Darrell and Alicia and Betty. When Miss Potts asked why she hadn't applied to the Cambridge colleges, she just smiled and said sadly that her plans had changed.
Darrell lives for today, but Sally knows that their beautiful, all-in-all life together can't last much longer. Darrell is ambitious, and she has young men flocking about her, asking her out for weekend drives and wanting to buy her teas. She'll move to London and end up marrying, and Sally will move back home to help her mother. Sally will watch little Daffy go to Malory Towers, and then she'll help her father with his office work, and watch Darrell's successes from afar.
What she can never, ever tell Darrell is that she would willingly do whatever Darrell asks. She would walk off a cliff if Darrell wanted her to. She would abandon the promises she made to her parents, she would even give up the chance of seeing Daffy ever again.
The power of this knowledge brings her up short. She has allowed what Darrell thinks to take her over so completely, it terrifies her -- and that is why she knows she has to get away as soon as she can, before she can't turn back.