This is a very tricky question and dark area of law.
--- no darkness is there,
here is the basic question
As per Indian Law, is forceful intercourse with wife an offence? If yes, does it come under rape or mental cruelty?
answer is this -
IPC Sec 375. Rape.--A man is said to commit "rape" who, except in the case hereinafter excepted, has s*xual intercourse with a woman under circumstances falling under any of the six following descriptttions:-
Sixthly.- With or without her consent, when she is under sixteen years of age.
Exception.- Sexual intercourse by a man with his own wife, the wife not being under fifteen years of age, is not rape.
as per ipc it will not be rape.
* if the wife obtained the order of "judicial seperation" from a competent court, and she refused to do s*x with her husband, - then it will be rape.