It is the opposite of love to endorse same-sex “marriage”.
From a purely non-religious perspective, it is something that has never existed in any civilization going back to its beginning - even in societies that required men to enter into homosexual relationships as part of the military training mandatory for all citizens (I’m looking at you, Sparta). Biologically, it is obvious that the genitals of men and women are uniquely suited for each other in a way that same-sex couples can never duplicate. Sociologically, any society requires children to be born at a rate of at least 2 per couple to survive, and more than 2 per couple to thrive - a function impossible for same-sex couples.
As you brought God into the discussion, I’ll continue with that theme: Scripture and Tradition are crystal clear on the point of sexual activity between members of the same sex - it is a grievous sin. Scripture and Tradition are also clear on the point that if one dies in a state of unrepentant grievous sin, one is going to Hell. If one is a believer in God and a supporter of same-sex “marriage”, then one is saying that they want people to go to Hell. It’s the equivalent of giving them a first-class ticket to the pit - the ride might be nice, but the destination is what matters.