Jungian Analysis on Gender as applied to this Film

In Jungian Psychology, the principle of being Feminine is to be Relational, and the principle of being Masculine is to be Principled.

This is the crux of the discord here:

Isabel wanted Lucy desperately to fulfill her relational capacity as a Wife & Mother.

And Tom had his moral obligation as a survivor of war, as a Lighthouse-keeper, as a man of principle, to be honest about the fate of Lucy & her father, especially once he sussed out Hannah's sorrow.