pookie's right - validation is a means to an end, not the end itself.
Pookie's also right that you can't make her feel anything. This is where validating below the words to the feelings is so important. It has nothing to do with agreeing - feelings are neither right nor wrong, they just are.
If she truly knows that her feelings, whatever they are, are being heard and accepted, then it will facilitate the possibility of the feelings changing (although there are no guarantees of course).
It is also likely that she is not completely clear about what her feelings actually are; in that case, validating them will help her get clarity.
Validating means unconditionally accepting her feelings exactly as they are without any agenda to trying to change them. (It's harder than it sounds)