§1. Although it is earnestly recommended that a spouse, moved by Christian charity and concerned for the good of the family, not refuse forgiveness to an adulterous partner and not disrupt conjugal life, nevertheless, if the spouse did not condone the fault of the other expressly or tacitly, the spouse has the right to sever conjugal living unless the spouse consented to the adultery, gave cause for it, or also committed adultery.
§2. Tacit condonation exists if the innocent spouse has had marital relations voluntarily with the other spouse after having become certain of the adultery. It is presumed, moreover, if the spouse observed conjugal living for six months and did not make recourse to the ecclesiastical or civil authority.
§3. If the innocent spouse has severed conjugal living voluntarily, the spouse is to introduce a cause for separation within six months to the competent ecclesiastical authority which, after having investigated all the circumstances, is to consider carefully whether the innocent spouse can be moved to forgive the fault and not to prolong the separation permanently.
Source: Code of Canon Law (Vatican.va)