You should tell him that you can play songs from Tabs and you wanna learn techniques and theory.
Maybe he thinks you are having lots of fun playing songs and that`s what you want. If you don`t tell him he won`t know.

Understanding Music Theory and mastering the different techniques will give you the chance of playing any song and what is more important create your own music.
This world can use some more good music. Don`t you think?