Big Sean has been leaning on his girlfriend Ariana Grande following the death of his grandmother.

The 26-year-old rapper - who confirmed he is dating the brunette in October - has been left devastated following the loss of his granny Mildred Leonard, who passed away last Friday (19.12.14) aged 93, but the 21-year-old singer is said to be doing a great job comforting him.

An insider told Hollywood Life: ''Ariana has never seen Sean so emotional in her life and she's comforting him as best as she can. His grandmother was such a driving force in his life.

''It's a somber moment for Sean, but it's actually bringing him and Ariana much closer together. He's leaning on her and she's as strong as a rock. This time is completely difficult for Sean and he'd be lost without Ariana.''

Sean took to his Instagram account last night (23.12.14) to post a picture of his grandma and attached a heartfelt tribute to her in which he admitted he was having a ''hard time'' accepting her passing and thanked her for making a ''better life'' for his family.

He wrote: ''My grandma passed away a couple days ago. I haven't said anything to anyone because honestly I feel like she's still here. I definitely can feel her consciousness. Im having a hard time accepting her death, but I must acknowledge my grandma's life, a true hero. She was a black female Captain in World War 2 (one of the 1st), got her degree at West Virginia State University, and her Masters degree at U of M. After school she became a police officer in Detroit, which at the time was very rare for women to be officers in Detroit. Then she became a caring teacher and counselor. She was the best grandma anyone could ever ask for. From the Sunday Dinners, home cooked meals, and how special she made us feel on our birthdays by baking us the cakes we loved most. She put her heart and more into anything she was involved in. She gave as much as she could to her family and the world! She completely made something out of nothing. When I was growing up, there were people interviewing my grandma about her life because she's done and seen so many amazing things. She supported me so much in every aspect and part of my life, even when I went against what was becoming traditional in our family, and didn't go to college to pursue music. She made a better life for me and the rest of my family, and I will forever be grateful I got to know and be loved by such an amazing woman! I'm so proud of her. She was truly a treasure to this world and everyone she came in contact with. She's the reason why I'm so passionate about giving back. Her spirit will live through her family. We miss and love u so much Grandma! (sic)''