The 28-year-old horse jumper has been dating Frenchman Elmaleh since 2012, and the couple welcomed a son, named Raphael, in 2013.
However, rumours of an impending split has been swirling for weeks and on Thursday (04Jun15), articles in the French press alleged Casiraghi had called time on the relationship after growing apart.
She was said to have had her belongings moved out of the Paris apartment they shared on Monday (01Jun15), but it appears any romance issues have since been resolved after Elmaleh travelled to St. Tropez to join Casiraghi and their son for a family day out on Friday (05Jun15).
Casiraghi is in St. Tropez for the Athina Onassis Jumping Competition, where she fell from her horse on Thursday.
Photos of her reunion with Elmaleh show Casiraghi in better spirits as she smiled and rested her head on the actor's shoulder, while he placed his arm around her waist.
A source tells People.com, "They haven't been seen together for some time, but what has happened between last weekend and then Monday - when Charlotte was at (Paris) Orly Airport with her son and her suitcases - and Friday morning in Saint Tropez, no one knows.
"Look, they're a young couple - only together three, three-and-a-half years. What couple do you know hasn't problems to work through?"
Casiraghi, whose mother is Princess Caroline, is eighth in line to Monaco's throne.