I agree with the comments, you are exceeding the reverse voltage spec of the opto LEDs and this is most likely what is causing the failures you see. The LEDs in the optocouplers are rated to 3 V reverse voltage maximum, and you hit them with 3.3 V.
There appears to be another problem with your design; you have insufficient current flowing in the LEDs to ensure the output can saturate. Assuming a +V of 12 V then to saturate the optocoupler output transistors requires just less than 12 mA. The optical conversion efficiency is only 35%, so this requires a minimum of about 4 mA through the LEDs. Normally you would increase the current to ensure you met all conditions, and I'd suggest the minimum LED current should be 8 mA.
To get 8 mA through the LEDs using 3.3 V logic with an LED VF = 1.2 V you need an R value of 270 Ohms maximum.
The top pair of optocouplers can be configured as self protecting since they are only driven by the FWD and REV signals.
The bottom pair of optocouplers need protection diodes across them. The maximum source or sink current is about 16 mA so this should be ok for any microprocessor output.
I hope the schematic makes sense since I only included the LED circuit stuff.
simulate this circuit – Schematic created using CircuitLab