There are some followers of a new paganism that refuses to recognize any force or authority higher than human claims or relationships. It's a kind of "I was nice to you so you have to be nice to me" mentality in which the speaker reserves the right to himself to define what "being nice" means. For these being nice means "you ate my food, you hung out with my friends, you have to come to my invalid wedding or marital-simulation ceremony. And if you don't you're wrong, it's personal, you've hurt me and you're responsible."
Except maybe there is someone more important than you and me. A higher authority who reserves to Himself the right to make claims upon the human race. A Being who reserves to Himself to decide what is right and what is wrong and demands that those who claim to love Him make choices that reflect such.
Catholics do not simulate sacraments and not participate in such simulations. God has spoken: a valid marriage is between one man-husband and one woman-wife. This means they cannot be of the same sex and cannot have been previously validly married to anyone else. Period.
God does not change. He is Truth and thus also His teaching on marriage is Truth. Truth cannot both be true and arbitrarily changeable at some possible future date.
Sometimes witnessing to one's Catholic Christian Faith entails getting kicked out of someone's house when all you intended was simply to wish the person a "happy birthday" over lunch.
Praised be Jesus Christ, now and forever. Amen.