The pair announced their split in April after five years together.
During an appearance on The Oprah Winfrey Show, the actress was questioned on the defining moment of when she knew that their time together was over.
"You know, the simple word I can give - and there's a few, so let me say a few," People reports her as saying.
"The first thing is, when it's not fun anymore, you need to start investigating and do an inquiry into the relationship."
McCarthy added that she rebounded well from the split due to her "warrior"-like personality.
"I checked into myself. How does my ego feel? My ego's fine. I'm a warrior mum. I always got back on my feet, and I know especially this year who I am," she explained.