Reading some of the reviews,,,its obvious that some people has never been the victims,were bullies themselves,and don't bullying and/or don't understanding the lasting effects that this has in people. I think Lila was in all he right to be cautious with Glenn. Bullying can have a lasting effect on people,mess with your self esteem,self worth,mental health and social life. Lila wasn't immature like some people commented here,she was in all her right to be the way she was around Glenn. And sometimes a simple "I'm sorry" doesn't suffice.
With that been said,I think Glenn should've done much more to gain Lila's trust and.trust,not just a few gifts cause he was her "secret santa"... Themes like bullying should be treat more seriously in TV shows and movies and not take like "kids will be kids"or "that was so long ago,get over it" kind of thing.
After all, I like the movie overall.