Input range of operation amplifier
As depicted, this could be a disaster (depending on how much current the AC source can deliver), because the 1 milli-Ohm resistor would cause the diodes to forward-conduct fully, so current is only limited by the AC source current and diode ratings. If the AC source is a tiny-current output (such as an oscillator or sensor) then this circuit should be ok, but the thing generating the signal could be damaged.

The solution as I see it is to omit the diodes and create a second voltage-divider off of Rshunt, such that a maximum (shorted RL) signal input would yield a maximum of +/-5v to the op-amp. You may want to make Rshunt a smaller value also, as the op-amp has gain already due to the 100k/25k. (If you need more gain, adjust these values.)

There is another issue, which the "Sense and Trip overcurrent-protection" may or may not address. That is that the op-amp output can vary from +5v to -5v (assuming it is a "true rail-to-rail" op amp. If an AC signal is applied to the op-amp, then an AC signal will come out - causing the relay to chatter on and off rapidly. Furthermore, an op-amp driving an inductive load directly (a solenoid) is probably not the most robust idea. So take that op-amp output, rectify it with a small signal diode, and charge up a small cap. Use this positive voltage to drive a darlington power transistor, MOSFET, or other suitable device to energize the relay. Make sure to use a fast diode anti-parallel to the coil, to prevent large inductive spikes when the coil is de-energized, from damaging the power switching device.