Just keep things separate. To me it seems there are a lot of red flags.
If you want to show your affection through financial arrangements, then add this person as POD on the account, review and amend beneficiaries declarations for brokerage and retirement accounts, and review and update your will, durable POA, and medical POA given your present circumstances. Today, these things mean more than making someone a joint owner of property such as a bank account. They also have the benefit of being changeable in the future if your circumstances change.
Joint ownership ain’t what it used to be: For example, Some states freeze half of a joint account on one owner’s death until they receive a tax waiver from an estate administrator.