Dogs can be more intimidated by men.
Some people, for instance, assume that their rescue dog has been hit by a man, but this is probably not so. There are much more likely reasons.
People in the training and behaviour field know that almost all shy dogs are more afraid of men than women, even if men have been nothing but kind to them their entire lives. See here what Patricia McConnell has to say.
I regularly go to dogs, usually rescue dogs, that are afraid of the very kind and loving gentleman and favour the wife. The men are quite hurt. Here is one of my cases where the dog was scared of men.
Theo Stewart, The Dog Lady
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