Seek Advice For Mental Harrasment

sir my sister is married to an indian air force officer,he married her with his consent and his parents consent as per islamic rituals...we gifted them what they demanded..but now he dont want to keep her with him...they have a daughter...presently she is with her mother in law...she is torturing her mentally...they pass nasty comments on her looks her shape....even his husband now dislikes her and keep on saying that he will take divorce but my sister wants to live with him.....they are married for two years....plz tell me what should i do..what are the rules in Indian Air Force for marriage...