By Jen Heger - Breaking Celebrity News Assistant Managing Editor

Good Morning America's George Stephanopoulos has told friends that he misses co-host Robin Roberts and is eagerly looking forward for her return from her bone marrow transfusion because Lara Spencer is driving him crazy with her childish behavior, Breaking Celebrity News is exclusively reporting.

"George is just absolutely miserable without Robin," a show insider tells Breaking Celebrity News. "He misses her being on set everyday and has a new appreciation for Robin's professionalism because he feels that Lara Spencer is extremely childish. Robin has always been a buffer for George and she is the person that brings the GMA family together.

"Lara has been grating on George's nerves and he is just counting the days until Robin comes back. George's background is hard news and he thinks that Lara just doesn't bring anything to the show."

As Breaking Celebrity News previously reported, appearing on GMA last month, Robin said she's "incredibly blessed to be doing as well as I am" and that while "it would be a whole lot easier not to be so public when you're going through something like this … it's a privilege to be a messenger."

The inspirational 51-year-old previously said about the procedure in her battle with MDS (Myelodysplastic Syndrome), a blood and bone marrow disorder. "Thirty-five days ago, I had my bone marrow transplant. It is a journey."

Robin also