1) If the wife is working, then the amount can be quite less.
2) If the wife owns a property, the amount can further be reduced (Section 25(1) of HMA).
3) Your other liabilities: house rent, medical bills for the amount spent on the treatment of your parents, liabilities towards sister(s), loan payments, provident fund, tax, etc.
4) Adultery or remarriage (Section 25(3) of HMA and Section 125(3) of CrPC) will lead to cancellation of maintenance.
5) Without any sufficient reason, the wife refuses to live with her husband (Section 125(4) of CrPC) . Use your wife’s failure to comply with RCR.
6) Both are living seperately by mutual consent (Section 125(4) of CrPC)