The Church does not disapprove of a loving relationship between same-sex individuals that is chaste and faithful but a sexual relationship between same-sex individuals as it is not in accordance with the divine plan of God. Same-sex inclination in itself is not a sin but as love often seeks to express itself physically, the challenge to be chaste and faithful to the divine plan of God is ever present.
-Archbishop William Goh: Pastoral Letter To Catholics With Same-sex Orientation
In the light of the unusual gesture by our local Archbishop to publicly legitimise celibate same-sex relationships as an alternative to marriage, I have a guess at how the Roman Church will cave in to the homosexual lobby while claiming that everything is perfectly consistent with their nitpicking canon law and constantly gerrymandered "Tradition".
First, in place of monogamous marriage, they will promote monogamous but sexually celibate same-sex relationships. Then these Roman same-sex couples will start entering into civil unions, not marriages. And since canon law and their tradition is essentially silent about civil unions, they would have no grounds to refuse it. Then some of them will be calling for church "blessings" of these same-sex civilly union couple. They will say, oh, we are not saying that we are celebrating the sacrament of marriage, just a prayer of blessing for our celibate same-sex relationship which is endorsed by the church anyway.
So how can they refuse? On what possible theological grounds can they say no? Which canon or church document can they cite?
Then what we have here is a normalised homosexual marriage in all but name. They will function exactly like a married couple, they will live together and do everything together, heck they can even adopt children because there is nothing in canon law which says they cant. And then now and then they will "fall into sin" and have sex, but then they can just go to a priest and confess on Sunday and everything will be a okay as their priest absolves them with a nod and a wink. Wash, rinse, repeat.
Thus, so what you have here is Church endorsement of gay marriage in all but name. But of course, everything will be perfectly legal according to canon law and perfectly consistent with the never changing Magisterium of the Church and everything will be all jolly and fabulous and great because all Jesus is concerned with is that his disciples obey canon law and believe documents generated by the Vatican bureaucratic machinery.
Dont believe me? The present Pope has already suggested the legitimacy of same-sex civil unions. It is a very real and distinct possibility.