One article I recently read states that the Buenos Aires bishops did not, in fact, teach what the headlines said that they had taught. The Argentine "bishops first speak about leading couples to live their whole lives in ‘the light of the Gospel.’ The guidelines explicitly state that, for many such couples, their path will not lead to reception of the sacraments. In cases where ‘both partners are Christians walking the path of faith,’ the Buenos Aires bishops state that they should follow the traditional teaching and refrain from conjugal relations if they wish to receive the sacraments."
Only then do the guidelines speak about the situation — presumably for couples where one party is not a Christian or is not practicing the faith — where abstaining from conjugal relations is “not feasible.” The situation foreseen here is apparently that of one party desiring such abstinence (like the Sonia example), but the other refusing and threatening dire consequences in the absence of conjugal life. The first party then agrees to sexual relations against his or her will, for example, to preserve the welfare of the children. This case could be treated in such a manner even before AL, according to application of the standard principles of moral theology and confessional practice.