Hi Ben,
Under the Common Travel Area (CTA), British and Irish citizens can travel freely between the UK and Ireland, so
UK nationals don’t need a visa or special permission to enter the Republic of Ireland, she can visit the Republic of Ireland just like you can.
Keep in mind that she might still need some form of photo ID (like a passport or driving licence) for the airline or ferry..
Also, if you are looking for inspiration for your plans in Dublin, these are some
popular activities.
Enjoy your trip to Dublin!