"They are spending a lot of time together. They're serious!" the source said of Kylie and the 25-year-old rapper. "She's really into him and has known him for a long time. Her family really likes him."
Kylie's older sister Kendall Jenner has also reportedly been "friends" with Travis "for years."
Kylie and Travis recently expressed their commitment to one another by getting matching tattoos of a tiny black butterfly on their ankles.
The sweet butterfly tattoo appears to represent Travis' new song "Butterfly Effect," which many fans speculate is about Kylie because when he released the song, he shared a photo of his girl exiting a private plane. The lyrics discuss needing a partner's love and being "stuck" on someone.
The couple's relationship is clearly going strong. Since getting together, Kylie and Travis have traveled together, attended NBA basketball games, enjoyed date nights and more.
An insider told Us in early May that Travis was "telling friends that he and Kylie are the real deal."
Kylie and the Texas-born, hip-hop artist have seemingly been inseparable since they were spotted getting cozy at the Coachella Valley Music and Arts Festival in mid-April, just weeks after the lip kit maven ended her longtime on-again, off-again romance with Tyga and he allegedly moved out of her $6 million Hidden Hills mansion in California.
Kylie's new reality show Life of Kylie is set to premiere August 6 at 9PM ET/PT on E!, so maybe Travis will make an appearance.
The network previously announced it had ordered eight, half-hour episodes of the new series that will follow the reality TV star's personal and professional life.
In a recently-released promo for Life of Kylie, the youngest member of the Kardashian and Jenner clan opened up about how she wants the person she's dating to be "obsessed" with her.