No matter how hard he tries, Scott Disick just can't catch a break when it comes to fitting in with girlfriend Kourtney Kardashian's family.

During a family trip to the Dominican Republic on Sunday's Keeping Up With the Kardashians, Disick felt more like an outcast than ever -- and turned to unlikely ally Bruce Jenner for support when his own girlfriend refused to hear him out. (His latest offense: Getting drunk and urinating in a trash can!)

PHOTOS: Kourtney shows off her pregnant bikini bod on vacation

"He's been in the family six years and he never feels quite worthy," Kardashian's stepfather Jenner reasoned after Disick was shunned by his girlfriend yet again.

Dad to 2-year-old Mason -- with a second baby, a little girl, on the way this month -- Disick told Jenner he's worried Kardashian will leave him on a whim because of his hot and cold behavior. "I've changed a lot of who I was because all I want to do is make Kourtney happy," Disick admitted. "I'm scared I'm going to wake up and she's going to tell me it's all over."

VIDEO: Kris Jenner slams Kourtney and Scott's relationship

Disick later told Jenner he's sick of Kardashian and her siblings treating him like he's not a part of their family. "No matter what, there's always something someone can find wrong with me," he said. "I feel like I've changed things about myself to be a better man, a better father, and there's always something someone can find. It's tiring me out."

Taking Jenner's advice to be more open with Kardashian, Disick confronted his girlfriend about a pact they had to get married. "The whole reason I had another kid with you is because you agreed to get married," Disick reminded Kardashian over dinner. "You broke the contract -- you broke the deal."

VIDEO: More about Kourtney and Scott's marriage pact

Though she may not have liked what he had to say, Kardashian appreciated her beau's candor.

Said the pregnant reality star: "I know that I'm indecisive but I'm not indecisive with you. I'm obviously committed to us. You're not disposable and I don't want you to feel that way."

This article originally appeared on Scott Disick: I'm Afraid That Kourtney Kardashian Will Leave Me