Justin Bieber was reportedly involved in a months-long romance with Kourtney Kardashian from 2015 until 2016, but are they still talking?

According to a new report, Selena Gomez, 25, who reunited with Bieber, 23, in October 2017, is concerned about her boyfriend's potential communication with the 38-year-old Keeping Up with the Kardashians star.

Gomez's “bizarre behavior” and concerns first started when Bieber and Kardashian turned up in Park City, Utah, at the same time, according to an In Touch Weekly magazine report via Hollywood Life on Jan. 17. As an insider explained, Bieber and Kardashian allegedly began texting each other after enjoying separate winter trips.

“When Selena and Justin got back together, she made him delete many girls from his phone contacts, and the first name she wanted removed was Kourtney’s,” a source told the magazine.

However, Kardashian reportedly failed to delete Bieber's number from her cell phone and began talking with him while he was away from Gomez. In turn, Gomez has been “acting erratically,” possibly due to jealousy over the ex-couple's past.

In late 2015, months after Kardashian's nine-year romance with Scott Disick, the father of her three kids, came to an end due to his inappropriate behavior with ex-girlfriend Chloe Bartoli, she began spending time with Bieber in Los Angeles. She even deemed herself a "Belieber" in March 2016 as she attended one of his concerts at the Staples Center.

Although Kardashian and Bieber appeared to be a full-blown couple, they never confirmed their romance, and in late summer of 2016, Bieber went public with his short-lived romance with Sofia Richie, who is now dating Kardashian's ex, Disick.

While the latest report from In Touch Weekly seems to hint at trouble in paradise for Gomez and Bieber, it isn't the first time fans are hearing about possible tension between them. Just last month, TMZ revealed that the couple was in therapy after Bieber admitted to contacting his ex-girlfriend, Hailey Baldwin, in an effort to make amends with the model.

According to the report, Bieber wasn't reaching out to Baldwin in a romantic way, but the interaction still didn't sit well with Gomez.

If Bieber is in contact with Kardashian, Gomez certainly wouldn't be happy, but she may not have anything to worry about. After all, Bieber is said to be happy for Kardashian and her new man.

“Justin is all for Kourtney finding happiness, especially with a younger guy like Younes,” a source told Hollywood Life last year. “Justin is much younger than Kourtney and finds her sexy, so he can understand what Younes sees in the eldest Kardashian."