The marriage bonds are often before the marriage, although they can be on the day. For instance, Robert Arthur married on 8th November 1771 but the bond was on 6th.
There is a will for Robert Arthur, of Dalar, Llanddwywe, in 1820. He named his children as Rees (surname Jones), Jane the wife of Robert Roberts, Dorothy, Mary the wife of William Lewis, and Catherine the wife of Richard Owen. I can't find all of the baptisms but Jane married as Jane Robert on 7th May 1803, bond on 3rd May, and Catherine as Catherine Robert on 16th March 1804 with the bond on the same date, but both surnames as Roberts.
Robert Arthur was a witness at Jane's wedding. On his burial, his year of birth was 1747, which matches the baptism as Robert Jones.
David
P.S. I can't find a Mary marrying a William Lewis, but there is a Mary Arthur who married a Lewis Lewis on 19th April 1805, with a bond dated 12th April. Lewis was a widowed mariner, and they had 6 children.