I agree that the attitudes to Lois's pregnancy haven't been very realistic. I can understand Douglas standing by her, because he's a kind and peaceful man at heart and he loves her to bits, but there would definitely have been more general social disapproval. Of course, illegitimate birth rates would soon soar (especially when the glamorous G.I.'s arrive) but even then it was really frowned upon and very tough for young women who wanted to keep their babies. A lot of children grew up thinking their grandmothers and aunts were their mothers.
As for Vernon, as much as I'm sure there were open and fair-minded men around who wouldn't have blamed Lois for her situation, they would still be in the minority. The likelihood of a man like Vernon (higher social class, officer in the RAF - which was still pretty class conscious and stuffy at the start of the war) being so besotted that he wanted to marry her seem, sadly, slim.
Generally, putting that aside and thinking of series two in pure 'drama' terms, I can see potentially interesting scenario's depending on whether Kasia survives the attack in Poland and comes to England with Harry, or whether Harry ends up widowed and definitely single. Lots of awkward situations for Lois, Harry, Kasia and maybe Vernon if everyone survives.
And Clawdy I hadn't even considered that Randy might be Helen Hunt's son (can't remember her name right now) until you mentioned it. Interesting, perhaps it is him and not the doctor in Paris. If the doctor had been the son born of that attack, would she have told him? I don't know. I guess all will be revealed in time.