1917 Code of Canon Law, Canon 1131

Civil Divorce, Civil Separation, and Separate Maintenance are all cases of separation of spouses for Catholics.  Reasons for separation are in two categories: 1) permanent for adultery, and 2) temporary for all else.

Regarding causes for temporary separation of spouses, the 1917 Code of Canon law shows in canon 1131 the requirement for the permission of the Ordinary (bishop).

Canon 1131. If the spouse affiliates with another sect; if he educates the children in another religion; if he lead a criminal or ignominious life; if he inflicts grave injury on the body or soul of the other party, if because of his cruelties the common life becomes unbearable, these and other like reasons become causes for separation by the authority of the Ordinary of the place, or by private authority if they are certainly verified and the danger of delay (entailed in going to the Ordinary) would be grave. (Translation by Very Reverend John D. Fitzgerald, J.C.D., Officialis and Vice-Chancellor of the Archdiocese of Chicago. Canon Law on Civil Action in Marriage Problems: Lectures Delivered under the Auspices of the Catholic Lawyers Guild (1944), pg. 43)

Can. 1131
§1. Si alter coniux sectae acatholicae nomen dederit; si prolem acatholice educaverit; si vitam criminosam et ignominiosam ducat; si grave seu animae seu corporis periculum alteri facessat; si saevitiis vitam communem nimis difficilem reddat, haec aliaque id genus, sunt pro altero coniuge totidem legitimae causae discedendi, auctoritate Ordinarii loci, et etiam propria auctoritate, si de eis certo constet, et periculum sit in mora.
§2. In omnibus his casibus, causa separationis cessante, vitae consuetudo restauranda est; sed si separatio ab Ordinario pronuntiata fuerit ad certum incertumve tempus, coniux innocens ad id non obligatur, nisi ex decreto Ordinarii vel exacto tempore.