love.mouse.getRelativeMode
Gets whether relative mode is enabled for the mouse.

If relative mode is enabled, the cursor is hidden and doesn't move when the mouse does, but relative mouse motion events are still generated via love.mousemoved. This lets the mouse move in any direction indefinitely without the cursor getting stuck at the edges of the screen.

The reported position of the mouse is not updated while relative mode is enabled, even when relative mouse motion events are generated.
enabled = love.mouse.getRelativeMode()
enabled boolean True if relative mode is enabled, false if it's disabled.