Amid whirling speculation, Sam confirmed the news on Saturday (29 November).
On his official website, Sam wrote: "I just wanted to update my blog today with a short statement as something I had hoped to keep as a private matter has found its way into the public arena this morning.
"As some of you may or may not be aware Tamera and I parted ways a while back."
His statement came hours after newspaper reports suggested Tamera had ended their relationship in order to concentrate on her career and to become Simon Cowell's next big star.
In The Sun, a source said: "Tamera had strong feelings for Sam, but she is also very ambitious.
"It wasn't her intention to hurt him, but she knew it was time to move on."
After coming fifth on The X Factor, 17-year-old Tamera was signed to Syco after Simon saw her potential to become the UK version of Rihanna.
Twenty-year-old Sam, meanwhile, is also focusing on his career and shows he has no hard feelings towards his ex-girlfriend.
In his published statement, he describes Tamera as "a fantastic person with incredible talent".
He goes on to say: "I am looking forward to watching her grow as an artist and go on to have great success. I'm also really glad we've been able to remain close friends."
Sam also shared details of his own music career, promising "some great music" in 2015.
Earlier this week, Tamera announced new music was on its way.
She tweeted: "Message to all of my fans! Thank you for being so patient, I'm taking my time so I can give you the best! I won't let you down."
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