The spelling of "fails keep" may seem confusing at first. However, it can be broken down phonetically as "feɪlz kiːp". The first syllable "feɪlz" is spelled with the diphthong "ei" which represents the long "a" sound followed by the "ih" sound. The second syllable "kiːp" is pronounced with a long "e" and is spelled as expected. "Fails keep" refers to a situation where someone or something continuously fails to maintain a certain level of success or achievement.