Cannot locate marriage of Imre Lippai and Anna Masa in Szeged (1866–1870

I'm researching the marriage of Imre Lippai (born 1838, died 1900) and Anna Masa (born 17 July 1848, baptized in Szeged, daughter of István Masa and Erzsébet Horváth).

I have located:

• Their children's baptisms in Szeged beginning in 1870.
• Known children include:
• Julianna Lippai (born 1871)
• Anna Veron Lippai (1874)
• Imre Lippai (1876)
• Etelka Mária Lippai (1879)
• Béla György Lippai (1883)
• Mária Rozália Lippai (1886)
• János Lippai (1893)

Despite this, I have not been able to locate their marriage in the indexed Szeged marriage records.

Are there additional Roman Catholic marriage registers, separate parishes, or unindexed records for Szeged in the period approximately 1866–1870 that I should be searching? Has anyone encountered this couple before?