My Russian neighbors asked me a question about credit cards.
They have five credit cards. 4 cards are in the husband’s name only.
And one is in the wife’s name only. If the husband dies. Is the wife
Responsible for the husband’s credit card debt.

The wife would not be personally responsible... however they could go after 1/2 of her assets, houses, cars etc so in the end she would have to pay it

What Happens to Credit Card Debt When Someone Dies? : Blogging Away Debt

If either of them dies the creditor, bank card, will go after the estate for the money. They will be in line ahead of the living spouse.