Here`s an example of how the 14th works,...You have the Right to keep and bare arms and the 14th says nobody including the Government may infringe upon that Right, it`s Constitutional law. Should you commit a Felony or gun related crime, you committed an act that gives up your right to firearms and you are no longer covered by the 14th.
There is no Constitutional law stating you must marry, therefore it is up to each State to regulate marriages and set guidelines or qualifications. All of these are State matters and the 14th can only be used if these regulations are broken, it does NOT write or approve of anything so only if these stipulations are broken can you refer to the 14th, You cannot use the 14th to write them or approve them but only to enforce them.
If those stipulation say same sex marriages are disqualified from said benefits, and you give same sex marriage the benefits,...you break the law. If the stipulation says same sex marriages are entitled to the benefits and you deny them, you break the law.
Each State has their own qualifications and the 14th ensures what they say is what they do. By nature of what they are(qualifications and stipulations) you can be denied but not discriminated against. Qualifications use discrimination to be met. That`s not a 14th issue.