I understand you love this girl very dearly. It's far better to generate self love. If your love is based off of external pillars, when the object leaves, so does your love. Far better to love yourself first.

Happines is a very tricky subject. I like to see it as a feeling rather than a thought. A feeling can only be felt in the body, not the mind. I think Happiness is a connection. Feeling connected to people and God. It gets hard when one tries to separate oneself and disconnect from everything.

It would be helpful for you to find out how you translate the word love. Google five love languages. It would revolutionize your relationship. It did to mine