My relationship with my wife is in crisis. I have agreed for her to leave the U.S. where we are living with our minor children, to Israel for a short-term visit, but now she is telling me, she is unwilling to come back to the U.S. with our children. Is she allowed to do so, legally?

No! a marriage crisis and/or separation do not justify a unilateral change in the minor children's country of habitual residence, or a reason for passive abduction by not returning them to their country of habitual residence. In this case you are advised to file for the return of your abducted minor children to the U.S. Our firm deals with such cases, successfully.