
Beau
Romantic Context
Use 'beau' when referring to someone's romantic partner in a slightly old-fashioned or playful way. 
Not for Women
'Beau' refers to a male partner, never a female. For a woman, you would usually say 'girlfriend' or 'belle'. 
Slight Elegance
'Beau' can imply a sense of class and charm, more than generic terms like 'boyfriend'. 