]So he didn't want to do anything that would give either of them the impression that a marriage could ever take place. I see nothing wrong with that.

True, I don't see that's wrong either. But something seems to be wrong. I think he should have shown more respect to his relations. I can not approve of him.

]...even she acknowledges that this is a private letter to a friend - it's not like he ever expected anyone else to read it

Yes, but the fact that he has written them does not speak well for him.