how would you react wen u find the person whom u love, doesnt loves u?

i also experience it a lot of times... last time when my girlfriend talk to me, i saw the power of love to the maximum... but nowadays, it's totally losing it... she doesn't sms or call me like last she did... even when times i didn't sms her, she would be so sad but now i'm feeling that pain... it's so hard to be like this...