in a rut
From Longman Dictionary of Contemporary Englishin a rutin a rutCHANGE/BECOME DIFFERENTliving or working in a situation that never changes, so that you feel bored I was stuck in a rut and decided to look for a new job. → rutExamples from the Corpusstuck in a rut• I sometimes feel my that my relationship with Jeff is stuck in a rut.