Bloom is starring in a revival of "Romeo & Juliet" alongside 26-year-old actress Condola Rashad, and Kerr is less than thrilled, reported Showbizspy.
After Bloom and Rashad recently flirted and kissed during a NYC photocall, Kerr became suspicious.
"She's steamed about how close they've gotten during rehearsals," a source said.
Kerr recently declared her belief in giving a man space in a marriage but is now afraid her relaxed views have backfired.
"Her friends talk about the hot chemistry between Orlando and Condola... She confronted him and he confessed to being taken with Condola but swore that was it. He insisted it was only professional.