Whenever a criminal charge is pressed against husband and additionally wife files for divorce based on FIR, it only means (without any abiguity whatsoever) relationship has ended atleast from wife’s side. There is no point in continuing with the relationship.
In such a situation law (and husband) should any way allow divorce. But additionally husband should be granted anticipatory bail to fight the 498a case. And if there is no evidence of physical injury caused to her, husband must be cleared off all the charges.