When it comes to cheating on his pregnant sister, Rob Kardashian isn't willing to forgive and forget. According to a new report, he believes that sister Khloe Kardashian should just move on from Tristan Thompson.

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Sources close to Rob told TMZ that he's still mad at Tristan, and even though the pair are reportedly getting back together and working things out, Rob is not having it.

Rob feels that Tristan is an "[expletive] hole" and it's impossible for him to let go of how he disrespected and embarrassed his closest sister when she was with child, the TMZ source explained.

Rob apparently disagrees with the rest of his famous family over their decision to support Khloe giving Tristan a second chance . TMZ reports that Rob is vehement that Khloe deserves better and should just move on.

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There is a silver lining, however, as TMZ sources also report that Uncle Rob is very excited to spoil baby True, whom he calls "gorgeous." He reportedly thinks that his own daughter, Dream, will be there for her always -- like he is for his big sis.