From Longman Dictionary of Contemporary Englishunfailingun‧fail‧ing /ʌnˈfeɪlɪŋ/ adjective ALL THE TIMEalways there, even in times of difficulty or troubleunfailing help/support etc I’d like to thank you all for your unfailing support. She battled against cancer with unfailing good humour. —unfailingly adverb The staff are unfailingly polite.
Examples from the Corpusunfailing• Her support in the last two months has been unfailing.• This is the unfailing attitude of the mind to all its problems. despite all its own beliefs to the contrary.• It was a well-proportioned house, Lissa decided, the lines drawn with an unfailing eye for symmetry and beauty.• Peter's unfailing humour made him popular with his fellow workers.• The only unfailing rule is, if they seem so, they can't be.• Lloyd George, in particular, was an unfailing source of repellent fascination to him.