In the last episode things finally become clearer to her (and as it happens, to Gilbert), especially after she consults the wonderful Miss Josephine, but even the latter does not tell Anne clearly, simply and concisely the SECRET of romantical love, which can be summed up in two short sentences:

1) If you have 'feelings' for someone, FGS TELL THEM. People are not mindreaders and may miss signs you give off consciously or unconsciously. They may be as insecure and uncommunicative as YOU are. So, TELL THEM DIRECTLY TO THEIR FACE HOW YOU FEEL. This may not be easy for all kinds of reasons, especially the fear of rejection, but it is the ONLY WAY to avoid misunderstanding and perhaps the tragedy of a love that might have been.

2) NEVER tell yourself that you are not "good enough". Firstly, what does that even mean? Secondly, it is not for YOU to decide you are not "good enough", but for the object of your affection to decide. If THEY think you are "good enough", then THAT IS ALL THAT MATTERS.

Both Anne and Gilbert had (as Diana tells Gilbert in the train) MULTIPLE opportunities to get it right, but chickened out: especially at the party after the exam results at the end of school. Of course, if they HAD followed the rules above we would not have had such a long-drawn out and entertaining saga!

I wish someone had told ME the above two rules when I was 16!

PS It was Gilbert (and thanks to Diana) who got it first. Had Diana not told him off on the train he might not have gone to see Anne at the hostel and kissed her (which in this case was as good as TELLING her how he felt).