Question

does force of friction always opposes the relative motion between the two bodies in contact

Answer 1

Friction always acts to oppose any relative motion between surfaces. For the simple example of a book resting on a flat table, the frictional force is zero. There is no force trying to move the book across the table, so there is no need for a frictional force because there is nothing for the frictional force to oppose.

Answer 2

No the frictional force never opposes relative motion between two objects rather it helps in their motion. For example if we want to write something on a sheet of paper and if no friction exists between pen and paper it would be impossible to write.