Its heartbreaking when a girlfriend leaves suddenly after having a close relationship. But, this happens many times.
Legally, I think you can not do anything as this is not a legal matter. Leaving boyfriend is not a crime. Its bad behavior .
I understand the emotional pain you are going through because of this break up. All you need to do is to peaces of your broken heart, heal yourself and keep your heart to give it to a more, sincere, dependable girl. I assure you that there are a lot of really trustworthy girls in India. Good Luck next time.