Although one would presume that u201cadulteryu201d would cover sexual infidelity in both heterosexual and homosexual marriages, the law does not see it this way.Section 1(2)(a) of the Matrimonial Causes Act 1973 states irretrievable breakdown of marriage can be established on groundsThat the respondent has committed adultery and the petitioner finds it intolerable to live with the respondentHowever, it is stated under section 1(6) of the 1973 Act (introduced by the Marriage (Same Sex Couples) Act 2023. thatOnly conduct between the respondent and a person of the opposite sex may constitute adulteryThis provision reflects the longstanding view taken by courts. In the case of Clarkson v Clarkson (1930), it was held that adultery is an act of sexual intercourse between a married person and a person of the opposite sex, who is not the married personu2019s spouse. Yet, in 2023. it is eminently arguable that this is an archaic formulation and paradoxical to the adultery provision.However, that being said, this would not mean that such a ground could not be used. Rather, although this would fall outwith the adultery provision under section 1(2)(a) MCA 1973, it would fall within the behaviour taxonomy under section 1(2)(b)That the respondent has behaved in such a way that the petitioner cannot reasonably be expected to live with the respondent.