38 CFR § 3.50 - Spouse and surviving spouse.
(b) Surviving spouse. Except as provided in § 3.52, “surviving spouse” means a person of the opposite sex whose marriage to the veteran meets the requirements of § 3.1(j) and who was the spouse of the veteran at the time of the veteran's death and:
(1) Who lived with the veteran continuously from the date of marriage to the date of the veteran's death except where there was a separation which was due to the misconduct of, or procured by, the veteran without the fault of the spouse; and
(2) Except as provided in § 3.55, has not remarried or has not since the death of the veteran and after September 19, 1962, lived with another person of the opposite sex and held himself or herself out openly to the public to be the spouse of such other person.