Since the gravitomagnetic force component Fg is not radial, it exerts a moment of force on the two-body system. This moment of force is negative during half cycle A and positive during half cycle B. This moment of force induces a negative rate of change of momentum known as torque during half cycle A and positive one during half cycle B. Thus an alternating torque, hence an alternating rate of change of angular momentum of the two-body system. There is no conservation of angular momentum as stated by the Newton law. The positive moment of force is always greater than the negative one. This explains the mercury perihelion advance. For more details see gravitational waves radiation
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