This is somewhat common- one spouse gets custody of the children, the other gets visitation. One weekend the ex doesn't bring the children back home.
82% of the child abductions nationwide were committed by family members.
(Department of Justice, Office of Juvenile Justice and Delinquency Prevention, National Incidence Studies of Missing, Abducted, Runaway, and Thrownaway Children, October 2002)
We're talking about roughly 150,000 children a year.
At some point you do still have to live your life, go to work, pay your bills and taxes. No reason you should be punished further by not getting a tax break because someone stole your child.