[Warning: The following story contains spoilers about Girls' sixth-season premiere, "All I Ever Wanted."]

Girls returned for its sixth and final season Sunday, ending its premiere with Hannah (Lena Dunham) basking in the laid-back vibes of Riz Ahmed's surf teacher Paul-Louis and the other staffers at the Hamptons surf camp she visits as part of a writing assignment. Hannah's and Paul-Louis' fling ends abruptly, just as she seems to be absorbing some of his peaceful, judgment-free vibes, when he casually tells her he has a girlfriend. But speaking with The Hollywood Reporter, Dunham says Girls viewers haven't seen the last of Paul-Louis.

"Riz's character comes back in a meaningful way later that I hope will be satisfying for people and you kind of get a sense of what she's gotten from him and what that relationship's meant," Dunham says, adding that she hopes Paul-Louis' brief return in the show's 10-episode final season "is emotionally resonant."

As for the immediate impact of his chill mentality on Hannah, Dunham says, "That can be hard to carry back to New York with you but I do hope that she's holding onto that sense of releasing judgment. I think that's a lot of what the episode is about — releasing judgment and embracing experience."

Elsewhere, Marnie (Allison Williams), who's still in a relationship with Ray (Alex Karpovsky), begins having the affair with Desi (Ebon Moss-Bachrach) teased in the trailer for the season. The divorcing couple begins making out after Desi consoles Marnie when she expresses some insecurity about her musical abilities. During their pre-makeout chat, Marnie also reveals that her and Desi's tour "was a total shit show" and that she's not inspired to make music now.

Speaking to THR, Williams says at the start of season six, roughly six months after the events of the fifth-season finale, Marnie's "in a freefall." The actress explains there's a connection between Marnie's insecurity and her infidelity.

"When Marnie first started her ways, Lena explained to me that this is her blind spot in terms of mistakes she makes most frequently and won't learn until something happens, some real introspection. So Marnie's infidelity, which always comes from a place of insecurity and wanting to ground herself with someone rather than just herself just shows itself in a new iteration," Williams said. "She's sleeping with Ray, who she's feeling a bit detached from because of his attention to and connection with Shoshanna (Zosia Mamet). And I think that Desi reminds her of a version of herself that she was really happy about. Inspired, musically active, creative. And so I think dipping back with him and the illicitness of it is something that appeals to her."

So how genuine are Marnie's concerns about her talent and future as a musician?

"I think it's just a moment when she feels really at sea, because I think she feels like she doesn't have a real partner in the game and she finds out, over the course of their weekend getaway, why it feels like he's not all there," Williams says. "But also I think she feels like she's not being herself to the fullest. So I think she's caught in this weird grey area where she doesn't have a partner but she's also not sticking up for and being the individual that she wants to be. So she's just floating, and when Marnie's floating she tries to tether herself to the nearest dick."

As for Ray's side of the relationship, Karpovsky says his character thinks things are going "swimmingly" but might also be ignoring signs of trouble.

"He's not a guy that picks up on even the most explicit social cues. I also don't think he wants to see the writing on the wall, see the little hints that things aren't correct between them. He thinks it's going pretty well," he says. And when asked how Ray would react if he finds out about Marnie's infidelity, Karpovsky says, "A part of him is very angry and disappointed, but a part of him is relieved because he sees a way out."

While all four girls weren't together in the episode, viewers did see Marnie and Hannah having a friendly chat as the latter was packing for her beach assignment. And some tension between Marnie and Shosh became evident as Marnie seemed uncomfortable about Ray's lingering closeness to his ex-girlfriend.

Although the fifth season ended with Hannah indicating she'd made her peace with Jessa's (Jemima Kirke) and Adam's (Adam Driver) relationship, viewers have yet to see Hannah and Jessa interact again but a preview for the season indicated that things were still a bit rocky between the two. The same preview also suggested that there would be other tensions among the four friends, with Marnie calling them together for a bathroom group meeting. While Dunham admits that "there's a lot of spoilers in the bathroom fight," she and the other Girls castmembers as well as co-showrunner Jenni Konner and executive producer Judd Apatow have indicated that the future of the four girls' friendships is a central theme in the final season.

"It's always been the central question of the show: Do you stay friends with the people you were friends with because you were roommates with them or cousins with them?" Konner says. "When we first started, people compared us to Sex and the City all the time and I was like, 'Those women made friends as adults once they had jobs and lives. They are staying friends.' I can guarantee you they are still friends because they were their chosen family, whereas with our girls, you just never know."

She adds that the tension in the group has been building since the fifth season if not longer, with Jessa's and Adam's relationship contributing to that.

"It's hard to make those friendships [last] as people grow and change and that felt like the real version of that to us of what life is," Konner says.

Going back to the bathroom fight, Dunham and Williams say the scene represents Marnie trying to fix the reality of the girls growing apart.

"Marnie's frustrated because what the audience has seen for so long, which is six years of characters who were at one point best friends growing further and further and further apart, she's finally becoming cognizant of and I think she, in her type A way, thinks that if she can gather everyone together she can fix it. But she realizes she doesn't actually have control over them," Dunham says.

Williams adds: "I think what she sees are four individuals who have grown apart. But there's no reason, since they're intelligent women with so much shared history, there's no reason why they shouldn't be friends now. But it's a very real moment to realize that a phenomenon of friendship is that as people grow up, occasionally, they grow up into versions of themselves that no longer fit as perfectly together or can't pretend any longer or are just tired of pretending that it works in that way.… After you've all lived with each other in various permutations, how can you declaratively say, 'I don't know if this works and I don't know how worth it it is? How much are we all getting out of this?' And Marnie's hoping dialogue will save all."