I've been thinking about this 'KJ should isolate herself' issue for the better part of the day or at least since I read this thread this morning, and I have to say that I disagree.
In my opinion we can't possibly compare a situation of real life management today to the one of a star ship stranded 70 years from home.
If I remember correctly, total isolation as you're talking about, JustKate, could be just as big a problem as the possible consequences of her having a relationship with her first officer or anyone else for that matter as they would all be under her command and so technically her subordinate.
Isolation does strange things to the human mind and I think it would pray on her mind over time. I don't know how much time, but she's a woman, she's human, and humans need contact.
I think it's unrealistic to expect any human being - man or woman, captain or crewman - to remain on their own for an entire lifetime.
She would have to be super human to do so and in the long run I think the crew would be better off with a happy captain.
Would it be difficult, yes. Not much doubt about that, but I think it would be just as complicated and difficult in the long run for her to remain completely without bonding with another human being.
Having said that I also have to wonder about the details about these two bad situations that you've experienced. I know it happens or I'm sure it does, but I'm just as sure that some people can make it work eventhough others can't.
*steps off soapbox*