"They're not even talking anymore," the source says. "That was made into a bigger deal than it was."
The DNCE singer was spotted locking lips with the 24-year-old Arkansas native last month in Mammoth Lakes, California. At the time, a source told PEOPLE the pair was "dating" but it was "nothing serious yet."
Serfaty had spent the holidays with Jonas, 26, in Las Vegas after meeting through a mutual friend, the source also revealed.
The relationship was Jonas' first after splitting from girlfriend Gigi Hadid this past fall.
Serfaty, who appeared on ANTM in 2010, shares a son with her ex-husband Ididia Serfaty. She was spotted leaving Hooray Henry's and The Nice Guy with Justin Bieber just last week.
Reporting by MELODY CHIU