The church does not say that a married couple must live together, but that they can separate and live in celibacy. Some monks and nuns in the early church were married, were both or one dedicated themselves to the religious life.

Going back on the indissolubility of marriage will undo the Church and its teachings.  

As far as I can tell both Matthew 16:24 Luke 9:23 and Mark 8:34 All record Christ saying that following him would bring hardship, suffering and the need for sacrifice. Our Lord did not incarnate to make things easier for us, but to lead us to sainthood.