The relationships on Girls are consistently inconsistent. People float in and out of each other's lives, lose and make friends, drift away, and then come back together. These kinds of pairings are at the forefront of "Old Loves," with couples navigating rocky roads, one new couple forming (Elijah!), and one friendship heading for an explosion.
Hannah and Fran (apparently both completely over last week's ex-girlfriend nudes scandal) now have a new disagreement: their respective teaching methods. Fran is very much a teacher — I'm assuming that he probably went to school for education and this has been a career goal — while Hannah, as we saw last season, sort of just fell into the job when her classes at her Iowa Writers' Workshop didn't go as planned and she retreated back to New York. Hannah prides herself on being a creative woman, both in her everyday life and in the classroom. When she gives her class an assignment to write a poem, Hannah grades them on creativity while ignoring simple grammar mistakes. Fran, on the other hand, urges Hannah to grade the papers properly, resulting in an argument that leaves one student's assignment ripped up.
This argument escalates when the student asks Hannah about the ripped paper, and Hannah marches her over to Fran's classroom to confront him — right as he's teaching a class. They continue to unprofessionally argue, to the point where the student gets uncomfortable and bails. Like most seemingly innocuous fights, this one is indicative of a bigger problem. It's not just about Hannah and Fran's different teaching methods (although Fran might be in the right here … ) but instead about how they are having problems communicating lately.
It's also possible that Hannah is lashing out a bit, uncomfortable with the fact that everyone keeps harping on how Fran is such a good guy, much better than the men she usually dates, and ha ha, Hannah, you better make sure you don't drive this one away! Even framed as jokes, these comments keep piling up, making her feel insecure in her own relationship, as if she's the bad person who consistently makes terrible dating choices and then destroys those relationships. It also doesn't help that none of her friends seem to be on her side. (Remember how Marnie didn't think the nude photos were such a big deal last week?) When she goes to vent to Marnie and Jessa, both are mostly uninterested in her problems — and Jessa especially so, though for obvious reasons.
Marnie and Desi's relationship is a bit on the fritz this week, too. The honeymoon phase is already over: They're back from idyllic vacation and in Marnie's cramped studio apartment. A small apartment is always going to result in arguments, especially if you discover your new husband (and some workers) loudly and messily building a giant wall in the middle of your home. Marnie has always complained about her apartment not having more space and Desi took "I need space" as a figurative thing — making the studio into a one-bedroom would give them more privacy — but Marnie literally meant more physical space, as in technical square footage. Marnie takes Desi's construction project as erasure ("I don't even fucking exist!"), as a selfish act that he's doing more for himself rather than for her perceived wishes. It's likely a mixture of both: Desi is trying to do something nice for Marnie, but he's also stroking his ego. And honestly, a little private space is probably a good thing for a new couple trying to make things work.
That's how Marnie also ends up at Jessa's, both she and Hannah annoying Jessa as she tries to study. (She certainly doesn't want either of them there to complain about their partners, an annoyance that is exacerbated by Jessa's weird little thing with Adam.) Marnie, uncharacteristically — or perhaps very characteristic of Marnie 2.0 — decides that she's the problem with Desi ("I'm the one building a fucking wall!"), instructs Hannah not to break up with Fran, advises her that "people who work on things stay together," before taking her own advice and making up with Desi. Also, Marnie and Desi's final scene is actually cute? Marnie 2.0 is kind, patient, and comforting. It's weird.
That leaves us with the fractured friendship. Enter Jessa, who is feeling guilty about her feelings for Adam, but nevertheless trying to find a way for them to be together. Her solution isn't to go the mature route and talk candidly with Hannah — likely because she's afraid Hannah will not approve, thus making her into a total asshole if she hooks up with Adam anyway — but instead, she actively pushes Hannah away. She's overly mean, telling Hannah that the internet is the reason why she isn't writing. At one point, she's even outwardly annoyed about having to pay for her small meal. "Maybe you don't want to be friends anymore," Hannah suggests as she calls her out, and she doesn't exactly disagree. Jessa then leaves to finally have sex with Adam — bad sex, for the record — and later glances up at his sleeping face as if waiting for the inevitable explosion. It's only a matter of time.