"Any way that seems reasonable" is not how the IRS guidelines suggest you split deductions. You are supposed to split pretty much everything down the middle if you make payments out of joint accounts and live together and don't specifically keep stuff separate. The exception is for property tax paid on a property owned by just one person, apparently. It says nothing about being the breadwinner, either, unfortunately. I think filing separately in order to pile all of the deductions onto the breadwinner's return would be a mistake, and potentially a red flag.
https://www.irs.gov/faqs/itemized-deductions-standard-deduction/other-deduction-questions/other-dedu...
