Wow. Is marriage a Constitutional matter? Perhaps. Is Open carry a Constitutional matter? Perhaps.
With marriage, one could say it's religious. Or they could say it's a government action. While that may not be covered by the 26 amendments, it could very well be that. But moreso than any of those, it is the one freedom that is covered in both the Holy Bible and the US Constiotution, and it has yet to be named specifically in the latter- the freedom of choice.
I am not gay. But no matter. What I do in my bedroom is my business, not yours. What you do in the privacy of your home is your business, not mine. I don't care if you enjoy foreplay while dressed like Hillary Clinton. It's none of my business.
Open Carry is a right that you have because of it's relationship to the Second Amendment. But it is not spoken outright ANYWHERE in the US Constitution.
If two men wish to marry and spend the rest of their lives together, that is their right. If anything I feel that a formal change in terminology is in place. "Marry" and "marriage" as general terms, and "civil union" & "matrimony" as more specific & descriptive terms.
If you feel that two men or two women do not have the right to live together married as they wish, then the right to Open Carry is also questioned.
Marriage, without regards to gender, is not a gay right, straight right, or any of that- it is a human right. Freedom of choice, if anything.