Catholic sex: past changes... and future?

I think there is a lot of truth in the Catholic Church's current teachings on sexual morality. In learning more about this aspect of the Catholic Church's teachings, one thing I find interesting is that, historically, many influential theologians saw things differently. For example, today natural family planning is (I think) a beautiful teaching of this church - my research into fertility awareness is what originally piqued my interest in Catholic theology. But this church's teachings on NFP only emerged in the mid-1800s, after secular sources started promoting early versions of the rhythm method.

On p.128 of the theology journal I recently acquired, I learn that St. Augustine (who lived in the years 354-430) "reject[ed] sexual relations during sterile periods because it is non-procreative". It wasn't just Augustine that held this view; William F. Murphy, Jr goes on to write that "strict adherence to "the Stoic doctrine" may have led, throughout the tradition, to a variety of overly-rigorous moral teachings in sexual ethics. Among these... norms against sex (i) during menstruation, (ii) after menopause, and (iii) for some primary purpose besides procreation."

Catholicism has always held that marital relations must have a procreative purpose. But to me, the shift from requiring procreation to be the primary purpose to requiring procreation to be a purpose is very significant. I find similarly important the shift on what constitutes consummation of marriage; on p.208 of the same journal, William May quotes Peter Jugis:

Due to Vatican II's teaching on modo vere human, canonists completely reversed their thinking on the manner of intercourse which was juridically appropriate for consummation. Prior to Vatican II the common canonical view opinion for centuries had been that violent consummation with an unwilling spouse validly consummated marriage.... After Vatican II the common opinion of almost all canonists became that a violent consummation with an unwilling spouse did not validly consummate a marriage.

To me, this reversal was important not only for women who are raped, but also for married couples where one or both has HIV. Prior to the addition of the modo vere human language to Catholic sexual theology, the marital act was largely defined as semen deposited into a vagina. Under that understanding, using condoms to prevent disease was definitely immoral. Under the current Catholic understanding, the morality of using condoms to prevent disease is a raging theological debate.

I am hoping for one more change in the Catholic Church's teaching on sexual morality: the acceptance of same-sex marriage. Currently, there are a few theologians arguing that the current framework of sexual teachings has room for homosexual marriages. The majority of theologians oppose such a move; they have a variety of reasonings involving the procreative and unitive nature of sex. They all seem to agree that homosexual acts are not contraceptive in nature; that makes the debates come down to the unitive aspect of sex.

From William May on pp.216-217:

In sodomy and other kinds of homosexual behavior the bodily joining of their practitioners... does not unite them.... the resulting experience is not and cannot be the experience of any real unity between them... In such acts, each one's experience of intimacy is private and incommunicable, and no more a common good than is the mere experience of sexual arousal and oragsm.

The person who recommended this theology journal, also sent me an article from the Spring 2005 National Catholic Bioethics Quarterly. Martin Rhonheimer wrote on p.44:

...one cannot swallow stones with the intention of nourishing oneself, nor are genital acts between persons of the same sex apt to be an expression of friendship and love.

A theological article in favor of same-sex marriage argued in part that those in homosexual relationships appeared to experience the same unitive effects of sex as those in heterosexual relationships, and that this apparent shared experience should be further investigated by Catholic theologians. Back in the Josephinum Journal, in a response to that article, E. Christian Brugger writes on pp.236-237:

...what warrants them in concluding that the reports of subjective experience... [are] sufficient... for overturning the... rational judgment against homosexual acts?... homosexual unions are not and can never be true bodily unions, [therefore] homosexual unions are not and can never be personal unions. Is the data of homosexual experience really so compelling that it overrides the reasonableness of this judgment?

I understand distrust of subjective data. But equally, reasonable and rational thought experiments need to match up with real-life experiments to be accepted as true. There are methods available to add objectivity to analysis of subjective data; I think that in time the evidence that same-sex marriage fits within Catholic theology will build. As a result, I believe the topic of Catholic sexual morality will continue to be very interesting for some time to come.