Rob Kardashian is "sad and sick" he didn't get invited on holiday with his family.
The 29-year-old star's famous siblings recently jetted off to Costa Rica for a relaxing break in the sunshine, and the television personality – who has two-month-old daughter Dream with his fiancée Blac Chyna – is rumoured to be hurt he has never been asked to join his siblings on their luxury retreats.
A source told HollywoodLife.com: "Rob has been sad and sick lately over the growing divide between him and the rest of his family.
"The sisters continue to go on family trips and film 'Keeping Up with the Kardashians' without him.
"Rob feels like his sisters are constantly judging and trying to direct his life. The whole situation has Rob feeling isolated and apart from the rest of his very tight-knit family."
However, it has been reported the 61-year-old momager Kris Jenner never fails to invite her only son along on their vacations, which he turns down because he doesn't feel "comfortable" or "welcomed" by the Kardashian/Jenner brood.
The source continued: "Even though Kris always reaches out to Rob and invites him on the family vacations, Rob simply does not feel comfortable or welcomed by the rest of the family."
And the Arthur George sock designer's older sister, Khloé Kardashian, 32, has rubbed salt in the wound by posting images of her with her sun-kissed tan on social media.
Alongside a picture of her sporting a lemon-coloured swimsuit, which was posted on her Instagram account, she wrote: "Island Vibes (sic)" alongside a string of palm tree emoticons.
And Rob's half-sister Kylie Jenner, 19, has followed suit and uploaded a string of images of her sporting skimpy two-piece beachwear as she cosies up to her rapper beau Tyga – who has four-year-old son King Cairo with his former partner Chyna – on the photo-sharing site.
She captioned one image: "volcano view (sic)."
And another read: "hola (sic)."