A married person abandoned by a spouse is not liable for the spouse's support until the spouse offers to return, unless the spouse was justified by the person's misconduct in abandoning that person, nor is a married person liable for support of a spouse who is living separate from the person by agreement, unless support is stipulated in the agreement.
Liability Of Married Person When Abandoned By Spouse
Mont. Code Ann. § 40-2-104, under Joint Interests, Obligations, and Powers.
Mont. Code Ann. § 40-2-104