I could not find Messier/Masy in my books.I did find your Marie Louise Lapointe, daughter of Guillaume Audet dit Lapointe and Marie Villers dit St Louis, in the book "French Families of the Detroit River Region" by Fr. Christian Denissen, page 689.It only lists her marriage to Mr. Cloutier.
I descend from a child of Guillaume Audet dit Lapointe and Marie Villers dit St. Louis.The Audet dit Lapointe's resided in what is now Erie, Michigan in Monroe County.St. Joseph Catholic Church in Erie, Michigan might be able to provide a marriage record. The church address is: 2214 Manhattan St., Erie, MI 48133.