Rituals(1998)

A woman confides in her best friend about her deep suspicions that her husband is cheating on her. The friend is into voodoo and spirits and gives her candles and charms to have around the house when the man of the house comes home. Suddenly he changes behavior and is asking her out to dinner, bathing in the tub together and generally getting back close again. So the voodoo seemed to have worked. So much in fact that the affair he was having becomes less important, much to the surprise of the "other" woman who turns out to have been fooling herself with her plan to keep him.