To become seemingly trapped or stuck in a mundane, non-changing pattern of life, work, and/or personal behavior. "I had so many ambitions when I first graduated from college, but now I feel like I'm in a rut." "We're stuck in a rut—let's move abroad for the summer and shake things up!" This example was taken from this site. https://idioms.thefreedictionary.com/be+stuck+in+a+rut

It can often mean "going nowhere," "trapped," or "unable to make any progress."