The moment loyalty requires dishonesty, it has stopped being about the two of you. A real friendship does not need you to cover a story, provide an alibi or say something untrue to an adult, and somebody asking for that is transferring the cost of their own choice onto you. None of the request is about care. It is about who gets exposed.

If you are asked this week, you can refuse without ending the friendship: say you will not lie and that you are still there for them. Offer the help that does not involve lying. A friend who only wants the lie was not asking for you anyway.