J.C. and the Bijoux Jolis — Katy Regnery

If the best man and maid of honor are both single, it's practically an unwritten rule that they should pork.
 
…so begins a rocky acquaintance between Jean-Christian “J.C.” Rousseau and Libitz Feingold at the wedding of J.C.'s brother and Lib's best friend. While manslut best man J.C. is surprised when maid of honor Libitz soundly spurns his advances, his curiosity is piqued. The girl he can't have becomes the only one he wants.
 
So, when he finds a seventy-year-old portrait in the attic of his sister's mansion that bears an uncanny resemblance to the prickly gallery owner, he enlists her help in solving a mystery seven decades in the making. Traveling from Philadelphia to New York to Marseille, a couple who started off as enemies will discover that even cynics can find true love…and mortal man is no match for destiny.