Well, online trees sometimes prove to be helpful when they happen to provide you with new leads.
I have found the marriage of Sophia Rousselle with Antoine Desjarlais mentioned in my previous post. It took place at the Catholic Parish of St. Mary of Victories, in St. Louis.
The record, written in Latin, reads as follows in English:
[…] on April 28  were joined in marriage Antoine Dejarlais, widower of 54 years of age, and Sophie Latour, widow of 44 years of age, in presence of the undersigned witnesses.