It has been proven by both experience and endless social science studies that marriage is best for children. Children raised in intact married families are more likely to attend college, are physically and emotionally healthier, are less likely to use drugs or alcohol, are less likely to engage in crime, and are less likely to get pregnant outside of marriage. The success of marriage directly impacts the economic wellbeing of individuals. Furthermore, the future of marriage affects freedom... We recognize and honor the courageous efforts of those who bear the many burdens of parenting alone, even as we believe that marriage, the union of one man and one woman must be upheld as the national standard, a goal to stand for, encourage, and promote through laws governing marriage."
To be perfectly clear, the Republican Party platform not only opposes basic rights for LGBT people, but also erases the very idea of our families. The underlying message in the language is that only heterosexual couples with children are "families," while any other make-up outside of that antiquated notion (including same-sex couples with children) simply aren't "real" families. In fact, the social science they refer to absolutely includes same-sex couples raising children, yet the GOP seeks to use distortion to erase our very existence.
Beyond that, the Republican Party wants to write that level of discrimination into our federal constitution-- they want to change the document they constantly wrap themselves in to take rights away from a specific group of people.
This platform shows a party taken over by extreme social zealots like Tony Perkins that want to strip LGBT people of their rights and drag forward social progress in our country to a grinding halt.