Travis Scott & Kylie Jenner. Picture: Instagram

The 19-year-old reality TV star and the 25-year-old rapper have decided to make their relationship official and have agreed not to see other people, TMZ reports.

And Kylie has even spent time with Travis' family in Houston, Texas, as their relationship heats up.

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Meanwhile, Travis has been telling pals that he and Kylie are serious.

A source told Us Weekly: "Travis is telling friends that he and Kylie are the real deal."

A post shared by Kylie (@kyliejenner) on

The cosmetics businesswoman was first seen getting close to the 'Antidote' hitmaker at Coachella last month as they strolled through the site together.

Twitter user: JaySos14 wrote: "Saw Travis Scott and Kylie Jenner making out during Dillon Francis set (sic)"

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And another fan used social media to share a video of Travis and Kylie holding hands as they walked through the festival with their friends.

The weekend before, Kylie "shared an awkward hug" when she ran into her ex-boyfriend Tyga just before Kendrick Lamar took to the stage.

A source said: "Kylie looked really sad as she walked away."

The pair went their separate ways to watch the performance and Tyga, 27, seemed displeased when Travis joined Kendrick on stage to perform 'Goosebumps'.

The source said: "Once Kendrick went on stage, Tyga and his crew were escorted to the front of the stage to watch the performance.

"[Halfway through Travis' song] a bodyguard began pushing through the crowd with a flashlight to get Tyga and his friends away from the stage.

"After Travis exited the stage, Tyga emerged on the side nearest the fence to begin watching again, as Schoolboy Q took the stage to perform 'That Part' with Kendrick."