O Amante de Minha Mulher (1978)

Alberto Verani is a married farmer and a relentless womanizer. When his wife Marina is away he tries to seduce Condessa Arduini sending her a bouquet signed anonymously. However Marina is the one to find the gift and hides it from Alberto, believing she have a secret admirer. So the husband keeps sending her flowers to test the fidelity while an outsider man discovers the plot and start to takes advantage of it.