Currently, you had the trigger to activate the grapple and then the grip button to fire the grapple, and you can let go of the grip and only have to keep the trigger held down.
My suggestion is that when the grip button is not being held, only the trigger, the grapple line should stay at the same length.
That way it gives the player more control when it comes to grappling, instead of the player automatically being pulled towards the grapple point.