Your query does not confirm that the spouse (wife) has left India with child, and is in foreign country. It does indicate that the spouse (wife) has plans to leave India with child.
If petition of spouse (Husband) fails in court of law it implies custody of child remains with other spouse (Mother) since child was with mother from the days child was infant to te date of divorce ( Ex. party) . The decision by court shall be crystal clear on custody with parent (Mother or Father), you be rest assured on IT………………..If the matter is agitated in court.
Until then you may not brand one spouse (Mother) as sole guardian (decided by court of law).
To leave India or not is personal decision of the spouse having child.
For the sake of future one can take personal decisions and need not wait till eternity.
Personal decisions are personal matters and are to be decided personally.
IT was personal decision of spouse (wife-mother) to not to contest divorce petition or let IT be converted to MCD on settle T&C o of which could be custody of child………..The elders of the family, mediators, counselors, Lawyers, shrude negotiators on both sides could have intervened to reduce the demands/T&C to acceptable levels, and reduced the accepted T&C in writing and accepted before court of law.
That has not happened.
Now IT is entirely the prerogative (even right) of separated spouses ( Ex. Husband, Ex. Wife) and mind IT child as well as far as custody of child is concerned to express before court of law…….