And you should not validate that point of view. you should not validate things that are not true.
truth: your wife is choosing to end your marriage
untruth: "there's nothing she can do to make it better".
validate truth. do not validate untruth. "validate", what IS actually "valid"!!!
I don't really even like the term "validation" as applied to relationships because the term "valid" does have a connotation of truth.
It is more helpful to me to think in terms of "feeling empathy" and "thought empathy", i.e. "I understand how you might be feeling and I care about your feelings" and, "I understand how you might see it that way." In other words, I see it more as understanding and acknowledging the other person's feelings and point of view.
Of course you can neither agree nor disagree with feelings, and even when people agree on the facts, they can have different points of view based on those facts.
I don't know if what I just said makes any sense. Validation can be tricky because you want to show understanding without agreement.