Problem with all those rulings is that marriage isn't mentioned by the Constitution. It's the ever so common, "The Constitution says what we want it to say".
I feel like you've got a somewhat skewed view of the Supreme Court. Their job is explicitly to interpret the Constitution, which in itself (being an extremely short governing document) is a loose framework that was never intended to specify every little thing but instead provide a general basis for government behavior and civil liberties in the country. Fortunately, unlike India's constitution, the U.S. Constitution doesn't attempt to cover every single little thing directly but instead provides a set of principles that the government must obey. Furthermore, by specifying the role of the Supreme Court and judiciary system as interpretive, it specifically recognizes their authority to understand and enumerate the rights protected by the Constitution.
This is common in a common law jurisdiction- in fact, this power of judges is the basis for common law (which, of course, is the basis for government in the United States federal government as well as 49 out of 50 states- Louisiana being the exception as it has a mixture of common and civil law).
Simply put, these justices weren't making anything up. They were applying
specific portions of the Constitution exactly as the Constitution demands they do.
Those 14 rulings were not them adding new content to the Constitution but instead comprehending the (deliberately vague) language of the Constitution. They specifically cited the Due Process Clause of the Constitution and identified the right to marriage as one of the liberties that the clause protects. Again, this was a power that was left entirely to them by the design of the Constitution and the wording of the Bill of Rights- it was
their job to use their rulings to determine exactly what these liberties constituted. That is
exactly the role of a judge in a common law jurisdiction- to interpret law (in accordance with existing precedents) and set precedents.
Regardless of whether you agree with their reasoning (and before you say you don't, I'd recommend you actually read the case briefs- they were written by people with far more training and expertise in constitutional law than you or I have- arguably the best interpreters of constitutional law in the country by the nature of their job, so the reasoning isn't as flimsy as you appear to think), the "it's not in the Constution" argument simply reveals a flawed understanding of the United States as a common law jurisdiction and the role of the Constitution within that jurisdiction. It's also demonstrably false
on face because there were specific constitutional citations provided in each of those fourteen rulings- citations that passed the test of time through Courts of multiple leanings.
This is exactly how common law and
stare decisis are supposed to work, and the judiciary branch doing its job.
Edited 6/29/2015 16:30:00