Physical couplets

An alexandrine game, best described by examples:

Inertia
They're together til something better comes along --
but it never will -- they think too much of themselves.

Gravity
Their singular attraction cannot be explained
by forces better grasped -- can they be serious?

Friction
There's the right way and wrong way to rub each other --
in heated exchanges they manage both at once.

To be updated as more moves arrive. Participation (where have you gone, Anselm Dovetonsils?) welcomed in comments, or wherever (any potential compilation elsewhere copylefted, should anyone care).