Meghan Markle and Prince Harry
Meghan Markle's sister doubts that her relationship with Prince Harry would last. Pictured: Prince Harry and Markle wave from the Ascot Landau Carriage during their carriage procession on Castle Hill outside Windsor Castle in Windsor, on May 19, 2018 after their wedding ceremony. Getty Images/Aaron Chown

Meghan Markle's half-sister, Samantha, thinks that her relationship with Prince Harry won't last.

In another interview, Markle's father, Thomas Markle Sr., revealed that he sent the Duchess of Sussex a birthday card but received no response. Markle's brother also said that if their dad was telling the truth, then she's abusing his love.

Markle's family is not happy with her silence. They are also mad that despite their father's efforts to reach out to her, there was no response from the royal. Due to this, Samantha said that her marriage to the Duke of Sussex won't work.

"If you treat your own father like this, Harry is next," Samantha said (via Daily Express).

She also called the new royal a "deceitful fake humanitarian." "There would be no just reason for her not to want him in her life, as he was good enough to use to make her everything she is," Samantha continued. "She should be grateful. Her diplomacy skills suck and are inhumane."

"Freezing people out is the best way of hiding the truth," she added. "There is no room for a greedy arrogant, deceitful fake humanitarian on this world stage. How dare she? Disgusting"

Samantha has been attacking Markle and Prince Harry online. Just recently, she questioned Markle's humanitarian effort and claimed that the Duchess of Sussex will never be the next Princess Diana.

"Humanitarians work towards resolve and peace," she said. "But my sister disposed of the entire family. There is no way to candy coat something so foul. What would Gandhi, Mother Teresa or the Pope say about that?"

She also attacked Prince Harry before the royal wedding and questioned his authority over Markle as he was not able to stop his wife from snubbing their family.

"Harry is a 'wuss' to allow the Duchess of Nonsense to mistreat everyone who has been close to her, especially her family. Diana would be ashamed. Stop wearing Meg's skivvies and bra and take your pants off of her!" Samantha wrote on Twitter.

Prior to the royal wedding, Markle's father made headlines after he agreed to stage his photos and received cash for it. Samantha took the blame and said that it was her idea. She reasoned out that he only did it to have positive photos for the benefit of the royal family.