I will love you, no matter what. I am marrying you, and even if you crucify and put me to death, I will come back from the grave to love you, because nothing can make me not love you. Marriage, you see, is central to what God is all about in Christ's incarnation. Marriage is all about commitment and belonging. Secular individualism is not.
Marriage is all about the generation and fostering of human life.
Secular individualism is not. Marriage is all about understanding about what kind of a God God is. Secularism seeks to dismiss God. Marriage is all about living together in a community, a community of committed love and bonded caring forever. Secular individualism is only about caring for the feelings of individuals.