A discussion between priests, in relation to this issue.
australianmarianacademy.blog.com/2012/04/16/marital-foreplay-discussion-fathers-david-watt-and-brian-harrison/
*One reason these theologians say that is because they look back in our tradition and, as I have said above, find hardly any written mention of oral or anal foreplay – either favorable or unfavorable. So they think, “Well, it seems the Church has never forbidden this. Looks like it must be legitimate! The existence of any law against such foreplay is doubtful; so couples have a green light to ‘go ahead’ here (if they like that sort of thing).” That would be the typical probabilist approach.
But it would not be mine. For one thing, arguments from silence can cut both ways: the silence might also be due to the fact that earlier Catholic bishops and theologians took for granted the sinfulness of such actions, considering them so obviously impure that it was hardly necessary to spell this out in writing.
For instance, Fr. Thomas G. Morrow has stopped holding his breath waiting for the magisterium to speak on this issue. Instead, he has boldly ‘taken the plunge’ and published an article expressing what millions of devout and chaste married Catholics have undoubtedly intuited over the centuries without ever talking about it (Cf. “Rethinking Marital Foreplay”, Homiletic & Pastoral Review, May 2010, pp. 58-63). According to Fr. Morrow, oral and anal foreplay partially simulate unnatural mortals sins, are therefore acts of lust that treat one’s spouse as a pleasure object rather than as a person, and consequently do not measure up to true standards of conjugal love and respect for human dignity. Thus, he concludes, such acts “should be considered illicit, in (or out of) marriage” (p. 63).
The total data available to me up till now ground a more probable opinion against that sort of foreplay, even though I can’t prove I’m right by citing a magisterial document condemning it. And as a probabiliorist, I will continue to tell Catholics who ask my opinion that those practices are mortal sins against purity and should definitely not be carried out.
We can say even more. Not only is it impossible to establish a consensus for Fr Harrison; there actually seems to be a powerful consensus against him (see above paragraphs 10-11); the most important part of which is not the contrary opinion of moralists such as Heribert Jone, but the silence of the Church. In the well-known legal adage, silence gives consent. The Church, while knowing full well that the above types of foreplay are happening, has not so much as breathed a whisper against them. Whereas if Fr Harrison is right, for the last 2000 years she should have been raising her voice like a trumpet.*