The fiery-tempered rocker exploded in rage at Nicole during a tour stop in Maryland in July. As Joel unleashed a very public, very brutal tirade — including the F-word — Nicole just stood there in stunned, submissive silence, a source reports. Now, insiders are concerned that this may be just the tip of an angry iceberg that could sink their eight-month relationship, leaving Nicole adrift and frightened. “I don’t see this lasting,” a friend of the couple tells Star. “And Nicole couldn’t handle being alone and a single mom. It would be too hard for her.”

The latest blowup came after Nicole, 25, who’s been accompanying Joel on his band Good Charlotte’s promotional tour, went into a lingerie store in Annapolis, Md., to buy a bra. Nicole asked for an AAA size — the smallest cup size available — but they didn’t have it, so she bought an AA. When she emerged from the shop, a furious Joel, 28, unloaded on her in the parking lot, says an eyewitness, drawing stares from stunned passersby. He was verbally explosive and even dropped the F-bomb while the waif like star took it all in silently. “Joel used to be a nice guy, but his temper is flying loose these days,” a friend reveals.