Honestly, I have always that making a big deal out of opposing gay marriage was unwise for the conservatism. Easy for me to say though, since I'm not opposed to homosexuality.
The reason for the opposition to Gay Marriage, at least at a movement/strategic level, was never about Gay Marriage. Heck, Democrat / Progressive support for Gay Marriage at a strategic level was ALSO never about Gay Marriage.
It was always about damaging Christian Churches.
Starting in the late 70s, but very much through the 80s and 90s, the "Moral Majority" was a major, MAJOR player in national level politics. It's organizational power was due to a few national organizations, but also due to the, well, for lack of a better way of putting it, the politicization of the conservative Churches in the US, them becoming politically engaged in a way they hadn't since the early 20th century. Part of this was due to the collapse of the fairness doctrine spurring the rise of Talk Radio. Most people think of Rush Limbaugh, but there was also a MASSIVE conservative Christian talk radio circuit, with many cities having an actual, outright Christian TALK RADIO station that tended to focus on broadcasts of sermons, actual talk radio shows that were basically local Christian talk radio, and also served as platforms for the radio messaging of organizations like Focus on the Family, etc.
This hybrid top down + bottom up organizing terrified Democrats, and served as major ways that Republicans ended up getting out the vote in the 90s. Plus these were media environments completely independent from the elite mainstream media that pushed the left wing narrative even then.
Further in this time you saw the explosion of homeschooling and conservative Christian private schools removing children from public education, getting better results on tests and outcomes, and these radio and organizations all worked to support and expand those efforts.
The issue was, they literally had no avenue to attack them, not legally at least. The Courts kept coming down on the side of home and private schools, quickly eroding attempts to litigate them out of existence, with the HSLDA (Home School Legal Defense Association) basically using the model of the ACLU and other old left wing civil rights legal funds to be an effective shield.
So what could be done? They needed an issue that they could in turn weaponize against these conservative Christian groups in a way that allowed them to be taken to court and bled dry, and an issue that didn't make them look like the bad guys. Also, direct attacks on private schools could end up backfiring on their own children who went to elite private institutions, after all.
Enter LGBT issues. Most, if not all, conservative Christian private schools and organizations have moral codes they expected their membership to hold to, which included basic Christian sexual ethics (you know, no sex outside of marriage, don't look at porn, etc.). LGBT issues could very easily be used as an attack avenue on these organizations, since many were non-profits but were not explicitly CHURCHES, thus Civil Rights laws did not have explicit carveouts for them. By pushing LGBT issues, they had found an issue where they could demonize these Conservative Christians AND take them to court for discrimination, they just had to get the laws changed to include "sexual orientation" as a protected class.
Which they then proceeded to do as much as possible, starting with state level laws, which they quickly turned on private schools and ideological organizations to try and force them to hire LGBT staff. The courts ended up giving some protections to these private organizations, but in general this was an effective avenue of attack, though one thing ended up standing in the way of this angle: Religious Freedom Restoration Acts. Which, you'll note went from completely non-controversial in the 90s when the Federal RFRA was passed by near unanimous votes in both the House and Senate and immediately signed into law by the President, but now state level RFRAs face very stiff headwinds from the Progressive left as they had proved a stumbling block for corrupting/dismantling these private schools and organizations.
What does all this have to do with marriage? Well, marriage in western civilization has always been understood to have a major religious component. The Catholic Church considers it a Sacrament, which is a Big Fucking Deal for them (it is on par with Baptism, it is THAT important), and Protestant churches also treat it as a major thing. Remember, much of these organizational efforts originated in Churches, and many private Christian schools are attached, again, to Churches. The long term goal of same sex marriage was to be able to use it as an issue to attack and damage Churches directly for refusing to perform same-sex marriages. The quiet part was
said out loud by O'Rouke in the Democratic presidential debates in 2019. Sure, the other ones denied it, but you can look around at how same sex marriage has been used to assail other private groups that aren't Churches to see it was always about damaging the conservative Christian institutional infrastructure and to marginalize and demonize them.
Back in the 90s, the conservative Christian media realized this and warned against it. That was why they fought as hard as they did on the issue, it was never about, to either side, the gays, it was always about destroying/protecting right wing institutions.
Now, did they go about it the right way? Probably not. There would been better ways to strategically handle the subject; however, that is hindsight talking, and what is past is past. But never, EVER, think that the Democrat's support for same sex marriage was ever about supporting LGBT rights, it was always, ALWAYS about damaging the right.