To further clarify:
When filing MFS, if one itemizes deductions, then both must itemized - even if the itemized deductions of one of you is zero.
If one takes the standard deduction, then you must both use the standard deduction - even if the itemized deductions of one of you would be higher. With the standard deduction you do not need to bother with entering the mortgage interest. However, if your state allows a deduction for property taxes, you should still enter your property taxes. Even they they may not help on the federal return, they could help on the state return.
