My girifriend told me that she does not love me on the phone! What Should I Do?

I been in relationship with my girlfriend for a year and a half! We had our bad and our good moments! These days she told me that she is very upset from my behaviour and that she does not feel one hundred happy with me! Yesterday, she told me that she does not love on the phone! Guys,please tell what to do! I am still in love with her, but obviously she is not! What I should do with this relationship! Please guys can you tell me, I will really appreciate your help!