There is a marriage on FreeBMd, Totnes registration district, June qtr 1864 5B 339, which only shows one spouse. There are normally 4 entries per page. It may be worth applying to the GRO for the marriage certificate, clearly stating the known bride and groom, the GRO will not issue a cert if the information given does not match. Civil registration started in 1837, so the marriage may well have taken place in the Register Office.