The three-part series has been penned by Public Enemies writer Tony Marchant, Broadcast reports.
The show focuses on the friendship between an unemployed former student and a married hotel events manager.
Described as a "character-driven story", Leaving is expected to focus on plots involving love, family, and issues to do with getting older.
Marchant has also penned shows such as Holding On and The Whistleblowers and the television movie The Mark of Cain.
Filming for Leaving is expected to begin in Cheshire next month.
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