Good morning Joandarc2008,
Start with the Catechism
2383 The separation of spouses while maintaining the marriage bond can be legitimate in certain cases provided for by canon law.[footnoot cann. 1151-1155.]
If civil divorce remains the only possible way of ensuring certain legal rights, the care of the children, or the protection of inheritance, it can be tolerated and does not constitute a moral offense.
Then go to canon law 1153 and canon 1692
Can. 1153 §1 A spouse who occasions grave danger of soul or body to the other or to the children, or otherwise makes the common life unduly difficult, provides the other spouse with a reason to leave, either by a decree of the local Ordinary or, if there is danger in delay, even on his or her own authority.
§2 In all cases, when the reason for separation ceases, the common conjugal life is to be restored, unless otherwise provided by ecclesiastical authority.
Can. 1692 §1 Unless lawfully provided otherwise in particular places, the personal separation of baptised spouses can be decided by a decree of the diocesan Bishop, or by the judgement of a judge in accordance with the following canons.§2 Where the ecclesiastical decision does not produce civil effects, or if it is foreseen that there will be a civil judgement not contrary to the divine law, the Bishop of the diocese in which the spouses are living can, in the light of their particular circumstances, give them permission to approach the civil courts.
§3 **If the case is also concerned **with the merely civil effects of marriage, the judge is to endeavour, without prejudice to the provision of §2, to have the case brought before the civil court from the very beginning.
It just makes sense. If divorce causes our spouse to commit adultery then we become guilty of causing the adultery. We should want to make certain we are in line with the Church as to when it would be acceptable to do this to our spouse.
Bryan
LOVE SO AMAZING