Lack of confidence made Abby ask her neighbor to substitude her to go on a date.
Lack of confidence made me tend to think too much.
This movie basically would like to convey a message:
"Inside beauty will shine through."
I'm sorry.
I partially agree with that.
Outside beauty is what people still have a desire for.
However,
there is one quote I do appreciate:

Brian:
You know how someone's appearance can change the longer you know them?
How a really attractive person,
if you don't like them, can become more and more ugly;
whereas someone you might not have even have noticed...
that you wouldn't look at more than once, if you love them,
can become the most beautiful thing you've ever seen.
All you want to do is be near them.

P.S. The above quote is from http://www.imdb.com/title/tt0117979/quotes