I have marriage details from the rootsireland website.
On 7 Nov 1872 Thomas Archbold, Athy, Roman Catholic, married Anne Smyth, Athy, Roman Catholic, In the parish of Athy.
Thomas' father was also Thomas Archbold and Anne's father was Patrick Smyth. There are no mother's details.
The witnesses were Daniel Smyth and Mary Carroll. I know that Daniel is a brother of Anne's so it looks like Thomas chose his future brother in law as his best man.
I suppose it's possible that either Thomas did not come from the Athy area or he did not have a brother.