Kylie Jenner and Tyga
According to Radar Online, the Kardashian family are 'worried' where Tyga got the money from for Kylie Jenner's diamond ring Christmas giftGetty

Their relationship has been thought to be on the rocks for a while now, what with unproven rumours circulating that the 8-year-age-gap between Kylie Jenner and boyfriend Tyga was starting to take a negative toll, interfering exes were getting in the way or that there had even been infidelities.

But now, after celebrating Thanksgiving and Christmas with Jenner's extended Kardashian family, there seems to be something else that is coming in between the young couple... a diamond ring.

Tyga, who has been dating Jenner since late 2014, attended Kris Jenner's Christmas Eve party, where he reportedly gave his girlfriend the ring. However, "Kylie's family do not know where Tyga would have gotten the money for that ring," a source close to the 18-year-old reality star exclusively told RadarOnline.com, and it is supposedly causing upset between the pair. "They advised her to get it appraised because they think that it could be fake."

The insider continued to say that because of the Kardashian's fears about her new piece of jewellery, Jenner is "terrified of founding out the truth" and "refuses to get the ring appraised" in case it comes out that it is in fact inauthentic.

This isn't the first time the flashy Christmas present has caused problems between the pair either. Just a few days after Jenner took to her personal Instagram account to share her gift to her followers, Tyga's transgender former fling, Mia Isabella posted on her own social media that the Rack City rapper got her the same present while they were allegedly together.

Isabella wrote alongside a video of her own right hand, adorned with a sparkling diamond ring: "Anybody can do that lol he bought me one too except I've had mine for years." However, Tyga has publicly denied he had any kind of romantic relationship with Isabella.

"Of course Mia caused a fight between Kylie and Tyga," the source later continued. "These days it seems like everything causes a fight between them. Kylie is just so overprotective of him. Even when she doesn't want Tyga, she still doesn't want anyone else to have him. Tyga told her that Mia was absolutely lying and that he never bought her any jewelry, yet alone a huge diamond ring."

The ring marks the second extravagant present that boyfriend Tyga has bought his girlfriend in 2015. Back in August, the 26-year-old treated the Keeping Up The With Kardashians star to a $320,000 (£215,000) Ferrari 458 Italia for her 18th birthday.

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A photo posted by King Kylie (@kyliejenner) on

Anybody can do that lol he bought me one too except I've had mine for years

A video posted by Mia Isabella (@themiaisabella) on