You just need to believe its there and love him back. . . Sometimes, it'll all depend on how u love him. Guys are human too, they know when u're for real, and sometimes thats all it takes to win a man over.
You only know, when the guy always atleast give you a call for 2 to 3 times a day and when he always like to see you and finaly, when he introduce you to her friends and some of if relative, i.e if you do go to his house to check on him.