Can these ages date each other?

Ok so I already made this post but I didn't give much context so let me explain better here. So my brother is 15 and a 10th grader and his girlfriend is 14 and a 9th grader. The age difference is 1 year and 1 month and I don't see an issue with them but I was thinking about the law since for a short time of like 20 days he'll be 16 she'll 14 and so on with 17 and 15 and 18 and 16. What I want to know is is this morally ok in your opinion and is it legal in the state of Georgia.