KUWTK: Scott Disick Worries Sofia Richie Feels 'Left Out' on Vacation with Kourtney Kardashian

Sofia Richie just made her Keeping Up with the Kardashians debut!

On Sunday’s episode of Keeping Up with the Kardashians, Kourtney Kardashian headed to Finland for spring break with her ex Scott Disick, their three kids and — last but not least — Disick’s girlfriend, Richie.

“I was first going to go to Finland as a girl’s trip, but it just seemed like a lot of the activities my kids would love. The dates that we were able to go ended up being Spring Break, and then Scott really wanted to come along,” Kourtney said. “And then it was my idea to invite Sofia to come on our trip.”

And while Disick was all for the plan, he knew bringing everyone together could create some complicated group dynamics.

“I never want to miss out on anything when it includes the kids,” he said. “The past six to eight months, we’ve been on a couple of trips where it’s been Kourtney, Sofia, the kids, and it’s been great. But Sofia mentioned to me that she feels a little left out so I have to be careful not to overstep anyone’s boundaries and make anyone feel left out.”

Kourtney, 40, and Disick, 36, ended their nine-year relationship almost four years ago but continue to co-parent sons Mason, 9, and Reign, 4, and daughter Penelope, 6. Disick and Richie, 21, have been dating for two years. Though the relationship initially raised eyebrows due to their age difference and Richie’s friendship with Kylie Jenner, Kourtney and her family have since warmed to the coupling.

Ahead of the trip, Kourtney explained to sister Khloé Kardashian that she didn’t feel awkward being around Disick and Richie.

“They don’t make me feel like I’m left out, which is nice,” she said. “Or else I wouldn’t go or invite her to come.”

Once on the trip, Disick admitted he was on edge trying to make sure everyone felt comfortable. Though Richie and Kourtney seemed to be bonding, he was nervous about Richie’s feelings.

RELATED: Kourtney Kardashian Explains Why She Invited Sofia Richie to Join Family Trip with Scott Disick

“Traveling with a family like this is a unique situation that not everyone does. I definitely think this trip, out of the other trips we’ve been on, has a little bit more pressure because the truth of the matter is, there are camera crews everywhere,” he said. “Tons of people walking around that Kourtney and I have known for over 10 years. Sofia has never really done anything like this before. It’s hard. I don’t want her to feel out of place, I don’t want her to feel like she’s not as comfortable as I am. I’m just trying to be cautious of everyone’s feelings.”

He continued: “Sometimes you have so many inside jokes or inside things with somebody you’ve known for so long, even if you’re not romantically with them, you don’t really know how to act. It is definitely a really hard and awkward situation, and I just feel bad. At the end, I want the people I love in my life to be happy.”

During a trip to see “Santa’s workshop,” Disick and Richie hung back while Kourtney interacted with the kids. After Richie said she was getting tired, Disick suggested they go home with Mason, who was already not feeling well. The sudden departure left Kourtney confused.

“I just think it’s really bizarre,” she said. “Mason was sleeping in the car, so Scott used it as a chance to just leave. We flew across the world to see this place, and just in the middle of it they just got up and left.”

She later confronted Disick while they are all in a hot tub together, calling him out for his “negative” attitude.

“First of all, I think it’s amazing for the kids … it’s just like a magical thing,” she said. “But you definitely were looking for a reason to leave. You could just say, ‘This isn’t for me and we’re gonna go.'”

RELATED: Scott Disick and Kourtney Kardashian Bicker While Soaking in Hot Tub with Sofia Richie on KUWTK

“Scott really wanted to come with us to Finland, so I don’t know why he’s just having such a negative attitude,” she added in a confessional. “I just want everyone to have a great time and a great experience.”

But Disick was’t oblivious to how the stress of having his current girlfriend and his ex-girlfriend spend time together was affecting his attitude. “It puts so much stress on me and then it turns into me being not happy,” he said. “Like I’m not even fun to be around for anybody.”

He eventually sat down to explain his anxiety to Kourtney, who encouraged him to relax. She even revealed that she offered to call Richie before the trip to help make her more comfortable.

“I think you put so much pressure on things to make everything perfect,” she said. “I don’t even mind if you [and Sofia] go off and do your thing, but if you’re in it, let’s enjoy what’s happening.”

Disick took Kourtney’s advice and went on a solo date with Richie before meeting back up with the kids.

“After sitting with Kourt and talking it through and communicating, which I should have done from the start, it definitely made things a lot clearer,” he said. “The truth of the matter is, I don’t need to put as much pressure on myself to feel like I need to do everything.”

After Disick loosened up, he admitted that his stress came from the fear of something going wrong and losing the opportunity to travel with his entire family.

“For me, it’s one of the best things I have in my life,” he said.

All in all, even Kourtney thought the trip was a success.

“it’s nice to be able to all go together and experience it together,” she said.

Keeping Up with the Kardashians airs Sundays (9 p.m. ET) on E!