To me, it’s just common sense that there CAN be some good to a relationship that involves “friendship, love, and mutual support”. That doesn’t in any sense cancel out the bad, sinful aspects of homosexual, adulterous, or merely unchaste relationships.
I think anyone who denies this is the case, but just hammers on how sinful and wrong certain relationships are, really loses credibility.
There are cases of immigrant men who leave their families at home, meeting women in the US, and winding up with two households, one in their home country, one in the US. Of course adultery is a sin, even in such circumstances, but I suspect that simply berating such men and telling them to cease living in sin, wouldn’t do much.
And certainly, if such sinful relationships produce children, a pastoral response is very complicated. And while same-sex relations can’t produce biological children, many in same-sex relationships do wind up becoming “parenting dyads” for children, whether biologically related to one of them or not.
That being said, it does seem that Cardinal Marx’s apparent support of same-sex civil marriage actually might be contrary to the Magisterium. But I’m not sure that the idea that there are positive aspects to homosexual relationships, is itself contradicting Magisterial teaching.