Lara is feeling pressure from all around. From her new friends who tell her to just enjoy life and to forget about personal responsibility, and from the high expectations of her parents and teachers. She feels as though she has no control over her own choices and is completely overwhelmed with the responsibilities at home and the weight of everyone else's opinions, choices and expectations.
Finally, Lara realised that she had to put everyone else's opinions to the side and focus on what she really wanted to succeed in. She stopped hanging out with the girls that only dragged her down and found a friend that was willing to work as hard as Lara was and looked as though she was in the same kind of situation.
Unsurprisingly, her marks began to rise as she wasn't skipping classes and didn't feel the pressure of the other girls pulling her down.