Not as far as I can tell. The closest example I can find is within-season pair bonding in copperhead snakes (defined as a male-female pair remaining together for some time, in this case defined as longer than a quarter of the breeding season).
Smith and Schuett (2015)'s abstract says:
Pair-bonding between sexes is common in vertebrate taxa, yet it has been noted far less frequently in some groups such as reptiles, and snakes in particular. Evidence to date indicates that many snake mating-systems are polyandrous, with both males and females having multiple partners in a single breeding season, and thus unlikely to exhibit lengthy pair-bonds. Wittenberger and Tilson (1980) suggested that pair-bonding exists when pairs remain intact for a consecutive period equaling at least 25% of the breeding season. Using this criterion, we present evidence of pair-bond formation in a North American pitviper, Agkistrodon contortrix (Copperhead), a species with a polyandrous mating system.
They observed one male-female pair that were found together over the course of 26 days out of a mating season of 70 days.
Uller and Olson (2018) say "in fact, multiple paternity in lizards and snakes is extraordinarily common and reach (sic) higher levels than that documented for any other vertebrate group": in their Table 1, the minimum level of multiple paternity observed in studies in snakes is 1/6. (Multiple paternity implies that females are mating with multiple males over the time scale associated with producing a single set of offspring. Genetic non-monogamy does not necessarily imply social non-monogamy — social monogamy + genetic non-monogamy is called extra-pair copulation — but it does suggest it ...)
Smith, Charles F., and Gordon W. Schuett. “Putative Pair-Bonding in Agkistrodon Contortrix (Copperhead).” Northeastern Naturalist 22, no. 1 (March 2015). https://doi.org/10.1656/045.022.0104.
Uller, Tobias, and Mats Olsson. “Multiple Paternity in Reptiles: Patterns and Processes.” Molecular Ecology 17, no. 11 (2008): 2566–80. https://doi.org/10.1111/j.1365-294X.2008.03772.x.