They made the mistake of putting together gay marriages and child adoptions. Many many people, not necessarily catholic, are strongly against the latter. And this is the result.
I know it's generally accepted that gay adoptions is a more liberal position than gay marriage but honestly that doesn't really make sense. If you oppose gay marriage, you might just be doing it for blind religious reasons and not have any especially negative feelings for gay people. If you oppose adoption, it's because you think all gay people are necessarily pedophiles.
