Francis seeks to avoid the errors of both 'liberals' and 'conservatives'
The very first Christians lived in a world that was alien to their values. One way in which it was alien was in its attitude to divorce. Both Jewish society, from which the first Christians emerged, and the Roman society in which Christianity took root, allowed divorce and remarriage. Men in particular could discard an unwanted wife very easily.
Christianity took a very strict view. Following the words of Christ, marriage was to be permanent and indissoluble. Some Christians allowed for some exceptions to this rule, but Christianity has never been lenient about divorce.
The early Christians could easily have accommodated themselves and their nascent Church to the mores they saw around them with respect to divorce. They could have concluded that they would make no progress in converting people to Christianity unless they adapted Christ's teaching. But they didn't do this. Instead, they adapted the culture.