A close family source – who revealed exclusively to PEOPLE that the former Olympian is dating Kris Jenner's best friend, Ronda Kamihira – says Kris's reaction to the new romance is not a factor for Bruce.
"Kris is devastated," says the source. "This was her best friend of 20 years, and Bruce isn't really concerned with her feelings about it."
Jenner, 64, and Kamihira were first spotted out together attending an Elton John concert in Los Angeles on Oct. 4, less than a month after he and Kris filed for divorce. According to the source, news of their budding relationship hurt Kris deeply.
"She is so sad, completely heartbroken and just truly shocked," the source says. Kamihira's children grew up with Kendall and Kylie Jenner, and the kids "have been best friends," says the source.
But despite the situation, Kris said publicly that she just wants Bruce to be happy. "I don't care who he goes out with," she said on the Today show on Monday. "He doesn't check in with me and give me a play-by-play!"
As for her own love life, Kris "doesn't have the time," says the source, adding, "she's not ready."
For more on how the Jenners are dealing with their split, pick up this week's issue of PEOPLE, on newsstands Friday