If one spouse itemizes the other must. 

If the first spouse to file itemizes, the second spouse must also itemize. 

If the first spouse to file claims the standard deduction, and the second spouse then itemizes, the first spouse must file an amended return to itemize. 

Itemized deductions are like a dominant gene.  If you have the brown hair gene, you're never going to be blonde.  At least, not without bleach.  

What's so difficult about that?  Dependents are first day of tax school.  Deductions are second day.