Good to hear this update. I do understand your wife, she has other priorities right now, but of course you all want to be one happy family... Good luck, and do keep us posted.
Fingers crossed for you all. I do hope you can sort this out. Could you see a dog behaviorist if there is one near you.
If Duggan is happier with you at home perhaps you need to have a rethink around some of the training and interaction with Duggan and perhaps for your wife to take more of a lead while you take a backwards step as it could improve their relationship a lot. I can fully understand how she has been feeling, one toddler, a baby on the way and a dog that had bitten her - that's a lot to be coping with when you are away ;( . I know you mentioned getting 'Mine' by Jean Donaldson and it would be worth your wife working through the training with Duggan and perhaps take the lead training rather than yourself if she feels up to it.