The pair have previously excelled in foursomes and fourballs at the Ryder Cup and Presidents Cup, but United States team captain Jim Furyk decided to put Spieth alongside Justin Thomas and Reed with Tiger Woods, with the United States losing 17.5-10.5 to Europe on Sunday.
Reed said after the loss that the decision took him by surprise, and Spieth may have been the driving force behind it, per the New York Times (h/t Bob Harig of ESPN.com).
"The issue's obviously with Jordan not wanting to play with me," said the Masters champion. "I don't have any issue with Jordan. When it comes right down to it, I don't care if I like the person I'm paired with or if the person likes me as long as it works and sets up the team for success. He and I know how to make each other better. We know how to get the job done."
Reed also said he felt the decision made by Furyk to leave him out in two of the five sessions was incorrect: "For somebody as successful in the Ryder Cup as I am, I don't think it's smart to sit me twice."
Previously Reed and Spieth had won four, lost two and tied one of their Ryder Cup matches as a duo.
In a disappointing weekend for the United States, the partnership between Spieth and Thomas was one of the highlights, as they won three of their four matches. Reed and Woods failed to pick up a point, although the former did win his singles match against Tyrrell Hatton on Sunday.
Golf journalist Jason Sobel doesn't understand why Reed is so aggrieved with the decisions made by Furyk:
Per Golf Digest's Joel Beall, the man dubbed Captain America following his previous Ryder Cup performances is never far from controversy:
According to Harig, there had been "rumblings" in the buildup to the tournament that Spieth wanted to end the double act with Reed, with the latter reportedly having said he had "carried" the former in previous matches.
"And earlier this year at the Arnold Palmer Invitational, Reed was dismayed when a rules official did not give him a favorable ruling and was heard to say that 'if I were Jordan Spieth,' he would have received it," added Harig.
Reed clinched his first major title this year at the Masters, producing an excellent display to win at Augusta National.
The Ryder Cup will be held at Whistling Straits in Wisconsin in two years. Whoever leads the United States' attempt to win the trophy back will hope tensions have died down between two of the country's best golfers by then.