Everyone has the right to marry the opposite sex. No discrimination what so ever.!!
And not everyone is permitted to be married: no incest, no polygamy, no bestial marriages, etc. So, there is good reason for folks to be denied marriage. 1. disease and body abuse, 2. marriage is safety net for women and children (see poverty level of unwed mothers), 3. it makes the community more dangerous...heightened risk of child abuse, 4. no reason for government financial benefits to those who have warm feelings for each other, there is for those with kids, and there are others.