Non EEA moved to UK after breakup and long absence

Asking for a friend. He is a non-EEA married to EEA wife. They have 3 children (EEA) of school age.
The family came to the UK in 2010, children went to school/pre-school.
In 2014 they all moved to France and lived there for 2 years.
While living in France, my friend and his wife separated. Their breakup is permanent but not divorced yet.
In 2016 his wife and children returned to UK.
The friend moved to UK too. He could enter as his EEA residence card was ok, but has expired by now.
What is the best route for him to apply to stay? His wife is not supporting with any documents.
Would he qualify for retained rights? (asking as he moved to UK in 2016 after breakup and long absence).

To qualify for retain right must be legally married 3years and must have lived together in UK for 1year..