if there are fields marked required in the table definition but not placed on the form and the data source for the form is the table itself Access will report that there are required fields left blank when you try to close the form.
Which makes perfect sense. Just because you don't add a required field to a form (which would be odd) doesn't mean that the fields validation is ignored. BTW, it would not matter if the recordsource was a query (instead of a table). Same result because the record is regarded as a whole.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.