I’m curious to understand how you came to this conclusion, that it has “no effect” on their lives. It so obviously does. Should someone of the Catholic Faith wish to express such an opinion they risk social ostracism and, perhaps, their job. If you meant that two gay people getting married doesn’t have a material effect on someone regardless of their opinion on it, well, there’s a certain pastry chef who would disagree with you.

I don’t really have a dog in that fight one way or the other. What I’m trying to point out to you is that these things are most definitely not “settled” issues if you think about them for more than the fleeting moment it requires to let everyone know how progressive you are. They likely never will be settled - unless you get your way and the “wrong” opinions are banned.