Well, in the case of the husband, I would be elegant with her and tell her something like:
"Please don't ask me how you look, because I am biased. I think you look stunning in everything."
But you asked about general white lies.
Like I said before, a harmful truth is not good at all.
I'm forever thankful to a doctor who, when I asked her if I can leave in 2 weeks, for my birthday, she hesitated for a moment, but then said:
I lay back down, happy, smiling, and thought:
"I can hold out for 2 weeks longer, but not for 3."
Had I known it would be 9 weeks, I would have been crushed, and that would have harmed my healing process.
This was one of the few times when people lied to me, and I was thankful, because they didn't lie for their own gain, but for mine. They gave me 'medicine'.
Forgive me when I quote the Dalai Lama in a Theravada forum once again, but he said something to the effect, that a white lie, if it avoids harm, is allowed, and then he laughed, and said:
"You gotta know the rules very well, so you know where you can break them."
Hope that reply was helpful, Stefan.