"So only her portion of their total medical expenses would apply"

No, that's what I am trying to clarify.

You told us the tax return is Joint, but the Account is individual. Things fall where they fall, and Retirement events are Individual, because the account is Individually Owned by that person.

Let's try this one: If the Taxpayer is over 72, and has no retirement account, and the Spouse is not yet 72 and has one or more retirement accounts, the Spouse does not have to take RMD. See how this is Individual, even if MFJ?