subjective 🙂 but honestly, I’d go with the Information Expert Pattern and say something like
library.lend(item, patron)
The library contains the information about the items it has (perhaps in its catalog).
The library lends the item to the patron (which it knows because it registers them)
Not sure how your instructor sees this, but this is the level of ‘abstraction’ (software objects mimicking real world entities) that would make sense for your scenario.