[Yahya (OP)]

gravity is tendency to fulfill displacement  in space caused by a mass M. the displacement in space is equivalent to the mass itself. space press mass and cause potential from positive(space existence) to neutral ( space displacement) force decreases by the increment in distance is because of the engineering of space , the same as pictures becomes smaller at far distances. if a have two masses m and M connected to each other by a bar and a third mass attracts them , then when they move farther from the third mass the force vectors should narrow to each other the decrease in the angle between the force vectors cause decrement in the force on the two masses m and M by the third mass , but the same could be applied on a mass m considering it consists of several masses