crawl back to (someone) with (someone's) tail between (someone's) legs

Translations
вернуться к (кому-то) с поджатым хвостом
After the failed project, he had to crawl back to his boss with his tail between his legs.
После проваленного проекта ему пришлось вернуться к своему начальнику с поджатым хвостом.
Definitions
To return to someone in a humbled, embarrassed, or apologetic manner after a failure, mistake, or defeat, often seeking forgiveness or help. The phrase evokes the image of a defeated animal with its tail tucked between its legs.