Kyle Howard loved Lauren Conrad -- but apparently not The Hills.

After the uber-private couple of three years announced the end of their relationship last Friday, insiders explain in the new Us Weekly (out now) that Conrad's reality roots irked the former My Boys actor.

"He saw the relationship as distracting from his goal of being the next Robert De Niro," a source close to the My Boys alum tells Us. "He wasn't supportive of her career."

Howard, 33, was usually a no-show at his 25-year-old girlfriend's business-related events -- and similarly avoided time with Conrad's friends.

"All of her friends can count on one hand the amount of times they've seen him," sniffs the insider.

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"Lauren is heartbroken" by the breakup, the pal adds. "She wants to be married and have kids."

For more details on the couple's shocking split -- including how Howard was "selfish" and not "supportive," the final nail in the coffin and more -- pick up the  new Us Weekly, out now.