Blush unseen can also be described as a hidden or concealed display of embarrassment or shyness. Alternative phrases that could convey a similar meaning could include 'a rouge in secret', 'a covert flush' or 'a surreptitious reddening'. Other synonyms could include words like 'bashfully', 'coyly' or 'reservedly', all of which describe subtle or subdued ways of showing shyness or discomfort. Whatever the chosen phrase, the idea is to communicate a sense of someone feeling embarrassed or uncomfortable, but not wanting to openly display their emotions. The phrase 'blush unseen' can therefore showcase a complex mix of emotions and social behavior.