From the 3 threads that you have provided, it seems that you fell out with your crush over some personal matters.
1. You declared your undying love for her during Christmas. However, she did not reciprocate although she did receive the sms. However, you did not clarify with her.
2. You still have feelings for her.
3. You no longer have feelings for her, but you are afraid that the feelings may rekindle due to you giving her tuition in English.
Presently, you realised that you do have feelings for her, but think that she treats you like dirt.
In addition, you mentioned that you do not understand girls, and that you are anti-social.
Have you ever ask yourself whether do you really like this girl, or is it just puppy-love. What do you really like about her. Before you declare your undying love to anybody, you will have to ask yourself these question and more. It is easy to say "I Love You". But, do you really mean it? Do not say for the sake of saying it. (Uncle just realised this recently
) Only when you have really answered all these question truthfully, then will you realised how much you really love that person.
As for understanding girls, Uncle is not able to help you on that. This is because Uncle do not have the answer himself.
Try to mix around with your friends more. If you dont make the first move, don't expect others to come and mix around with you.
Good luck in your studies and relationship