I'm right handed and left eye dominant. Shooting a rifle is no problem as previously noted since I close my left eye. With a shotgun, I have shot right handed, left handed, both eyes open, one eye shut. After all this, I just felt better shooting right handed with both eyes open. Also as noted before, you point a shotgun not aim it.

That said, I think you are doing the right thing figuring out what works best for your wife, especially since she hasn't develped any bad habits yet.

Good luck