My dog is acting wrong for this time of month, psychological issue?

Now we all know its mating season, dogs should be going wild, running outside, the pillow etc... Sadly my dog, Bruno a big strong sausage dog isn't doing this. He seems to be often sad when looking out the window but kinda reluctant to go out, depressed? He also seems to be walking around with a serious bone on but not the sofa like other dogs but seemingly without encouragement will unload in the pallet for dog biscuits and eat them. I'm unsure if the depression is a natural state or should he be seeing the vet? I know dogs do weird things in our eyes like smell each others s and eat poo but this is a first. Should I be concerned and take him to the vet?