A coupling assembly for elongate elements includes a pin having an outward-facing pin surface, and a box having an inward-facing box surface. The pin surface and box surface are configured for mating engagement. At least one bore has a port configured for connection to an injection fluid reservoir as a first opening and a second opening penetrating the pin surface or the box surface. A region of the box surface can include a wall thickness less than the thicknesses of the adjacent box walls. A region of the box surface can also include a material of a lower mod ulus of elasticity than the material of a corresponding region of the pin surface, or vice versa. A region of the pin surface can include a wall thickness which is less than the thicknesses of the adjacent pin walls.