Bruce Jenner 'I'm Not That Excited' About Kim Kardashian and Kanye West

Not so fast, Kanye--you've still got one very important member of the Kardashian crew to win over.

During a speaking engagement in Boston Wednesday, Kim Kardashian's stepdad Bruce Jenner told the audience he's "not that excited" about Kardashian's latest fling with Kanye West.

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"I'm not that excited, but we'll see," Jenner, 62, told the crowd. "Kimberly and I have had a conversation about them and their potential relationship."

Jenner's chief concerns don't seem to be West -- but instead, his stepdaughter's penchant for jumping quickly into serious relationships. (Kardashian is still locked in a bitter divorce battle with her soon-to-be ex-husband, Kris Humphries.)

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Kim's sister Khloe Kardashian told Ellen DeGeneres earlier this week that her big sister and the rapper are "cute together."

Kim has talked before about her tendency to get too invested in flings too quickly--she told Glamour magazine earlier this year that she's a "hopeless romantic" and believes "in love and the dream of having a perfect relationship."

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Sources tell Us Weekly that West has pursued Kardashian "for a long time" -- and now that Kardashian is single again, the timing finally seemed right for the Grammy winner to step in.

West, 34, and the E! star enjoyed a marathon, 48-hour date in New York on April 4 and 5; the duo dined together at New York hotspots Serafina and Cafeteria, caught a screening of "The Hunger Games," hit FAO Schwarz, and managed to squeeze in a couple of sleepovers.

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Still, it took some time for Kardashian -- who initially saw West as just a friend -- to come around. "Now that Kim has gotten over the Kris drama, she sees how much Kanye loves her," a source close to the star tells Us.

As for West? "[He's fallen] genuinely head over heels," an insider close to the rapper reveals. "They're perfect for each other. He thinks she's his Beyonce!"

For much more on why this romance is the real deal -- how Kim finally got over her ex Reggie Bush, all the details on their high-profile New York dates, what Kris Humphries thinks and more -- pick up the new Us Weekly, on stands Friday!