(one) might be forgiven for (doing something)

It is completely understandable that one would do, think, or believe something, even if it is incorrect. Anyone visiting this country might be forgiven for thinking that they've somehow gone backwards in time. You might be forgiven for wondering how a multinational company has failed to pay its taxes for the last five years. A: "Wait, Ron and Elise are dating? I thought he was her grandfather!" B: "Well, you might be forgiven for that—Ron is 30 years older than her and has had white hair as long as I've known him."