When it was announced a little more than a year ago, it felt to many like a sure thing.

After all, government regulators had approved Comcast’s acquisition of NBCUniversal in 2011. Comcast had an army of registered lobbyists, more than 100 strong, in Washington alone. The company’s chief executive, Brian L. Roberts, golfed on Martha’s Vineyard with President Obama. Its executive vice president, David L. Cohen, hosted three fund-raisers for Mr. Obama, two at his home in Philadelphia, raising a total of more than $10 million.

But now the $45 billion Comcast-Time Warner Cable merger is dead. Comcast is folding, in anticipation of regulators rejecting the deal.

The news, which broke on Thursday afternoon, was certainly dramatic. But the air of inevitability that once hung over the deal had been dissipating for months, as the debate over net neutrality — in short, the question of whether Internet providers should be allowed to charge content providers for speedier service — played out in Washington. And a merger that had at first seemed to be primarily about cable television turned into something much different.

The government’s verdict on the merger and its stance on net neutrality were separate issues, but they were very much intertwined. At the end of the day, the government’s commitment to maintaining a free and open Internet did not square with the prospect of a single company controlling as much as 40 percent of the public’s access to it. All the more so given the accelerating shift in viewing habits, with increasing numbers of consumers choosing streaming services like Netflix over traditional TV. In this sense, it didn’t really matter if Comcast and Time Warner’s cable markets overlapped. The real issue was broadband.