The ethics of travel romance

A Montreal friend with a public profile recently visited South America and met this lovely young sprite and the young duo shared an instant chemistry.    They were firing up the Bunsen burner and he was checking out her periodic chart.
   He could only snap her here furtively because a previous local boyfriend was also on the scene.
   So should gringo disrupt the natural, organic time-honoured social customs of South American scheme of relationships that has been working there for centuries by persisting in pursuing her affections, or should he back off and allow the previous boyfriend have her, who, for all I know paid three oxen and a dozen chickens for her?