Under the last-month rule(LMR), you are considered to be an eligible individual for the entire year if you are an eligible individual on the first day of the last month of your tax year (December 1 for most taxpayers)
and you meet certain other requirements. If you meet these requirements, you are an eligible individual
even if your spouse has non-HDHP family coverage, provided your spouse’s coverage doesn’t cover you.
However, if you use the LMR you must remain eligible through 12/31/2024 see IRS PUB 969 starting on page 6
there is no requirement to use the LMR in which her eligible contributions are prorated for the year
https://www.irs.gov/forms-pubs/about-publication-969
