Kourtney Kardashian: Why I Won't Marry Boyfriend Scott Disick

Kim Kardashian may be heading down the aisle later this year to swap vows with Kris Humphries, but don't expect her sister, Kourtney, to follow suit.

In fact, 31-year-old Kourtney says she's perfectly fine without saying "I do" to her longtime beau -- and the father of her 18-month-old, Mason -- Scott Disick.

PHOTOS: Scott and Kris join the family on vacation in Bora Bora

On Sunday's episode of "Keeping Up With the Kardashians," Kourtney faces criticism from Kim and their mom, Kris Jenner, when she contemplates having a second baby out of wedlock. Concerned for her daughter, Jenner, an ordained minister, goes to the family's pastor for advice on how to convince Kourtney to wed.

"That's not up for discussion, nor do I care what anyone's thoughts are," snaps Kourtney in a preview clip from Sunday's show.

VIDEO: Kim fumes over Kourtney and Scott's gross PDA

Jenner, 55, has clearly turned a corner when it comes to embracing her daughter's once hard-partying beau. As a result, she's trying to rush them down the aisle.

"When Mason was born, Scott was more of a hot mess, but now he's really turned his life around and been amazing," she says in the clip. "He's such a great partner to Kourtney. I don't know what Kourtney's reservations are, why she's holding back and being so stubborn." Seconds Kourtney's sib, Kim: "I don't know where Kourtney's coming from. I actually agree with my mom on this one."

PHOTOS: Mason's most adorable moments

And although Disick went so far as to shop for engagement rings on last season's Kourtney and Kim Take New York, his girlfriend doesn't seem like she'll be changing her mind any time soon.

VIDEO: Kim joins Scott to shop for engagement rings

"I definitely don't want to get married just for the sake of getting married," she reasons. "This is my life. I don't need a piece of paper to make it a family unit. I don't want to get married right now [and] I don't have to listen to my mom or anyone else!"

Check out more of the family's emotional confrontation above and watch the full episode of Keeping Up With the Kardashians Sunday at 10 p.m. (EST) on E!

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