@HOOfan_1 If that were the case, I would consider it bad story telling, since nothing like that has been hinted at in the flash backs.
In fact I don't consider the shown reason that strange. She started to study to impress her brother (and family). But with her shutting out all connections to her brother, she doesn't have anything else to proove her worth. In her own eyes being the best in her year is her character trait. If she would loose that, she would loose her own self worth, since she shut out her own family and also doesn't seem to have friends (because she is studying all the time...). But now that she has re-established a connection with her family again, being the best isn't the only thing driving her anymore.