Own a house with fiance. Can one person file itemized to take advantage of mortgage interest and property tax deductions ~$33k and other take standardized deduction?

[xmasbaby0]

Since you are not married you can each file the way you want to.   it is only married couples who have to file the same way when they file married filing separately.  You cannot file a married return.

[AmeliesUncle]

You can only claim the amount that you actually paid.  So if you paid the full amount and your fiance paid none of it, yes, you can do that.  But if you both paid them, you can only claim the amount that you actually paid.