Of all the conversations to transpire during the series, Oliver confronting Shane about reading his letter in A Hope & A Future is perhaps the most gently heartbreaking of them all.
The canceled dance lessons and first argument were merely catalysts moving Oliver ever closer to finding a future, or closure, in his relationship with Holly. But it is the conversation between Shane and Oliver in the series finale that brings the conflict to a head, leaving both uncertain of what the future holds.
Then Oliver wrote his letter to Holly in the vault during The Treasure Box, and she slowly began to re-enter the fray. By the time we reach the series finale, the letter is written and ready to be mailed.
Shane happening upon the letter might seem exclusively a matter of temptation---but compare it with that moment in the Pilot when she swiped Kelly's letter to Charlie, desiring to know how the story continued. In that instance she straight up swiped the letter, regardless of whether or not she read it. When confronted with Oliver's letter here, Shane's hesitation, causing her to debate the issue with Rita indirectly, is a result of fear. As much as she wants to read it, to maybe know where she stands with him, she's afraid.
What Are You Afraid Of?
It all started with Shane wondering if Rita and Norman would ever "tell each other how they really feel." Shane has always been keen to the state of their relationship. And, more often than not, Shane and Oliver have subconsciously used Norman and Rita's relationship to help navigate and negotiate their own. In some ways this interaction between Shane and Oliver proves no different, as pondering the "will they, won't they" applies as much to them as to Norman and Rita.
What I find particularly noteworthy about this interaction, however, is the fact that Oliver recognizes Rita's pursuit of pudding as something to be associated with love. This is the second time Oliver acknowledges something as love, without having to be prompted or convinced (the first time was an episode before, when he identified "love" being in the safe deposit box). In fact, Oliver goes even further to suggest that Rita and Norman are inevitable as "true love cannot be held at bay forever, no matter how hard one fights it." It's clear Oliver's perspective is beginning to shift.
This is also the conversation in which "...ways to say 'I love you' without actually saying [it]" is introduced, which finds expression almost immediately through Shane's near-monologue lamenting the letter and phishing for its contents.
Brave. Beautiful. Heartbreaking.
When I think of Shane's words---her honesty---with Oliver in this moment, these are the words that come to mind. Shane needed only to defend the fact she didn't violate the sacred trust of leaving his letter unread. Instead, she went a step further, revealing her heart---and even her fears---to Oliver.
Not surprisingly, Shane interprets Oliver's silence on either point as rejection, causing her to retreat back to reassuring him about not reading the letter more generally.
Displaced, she makes one last attempt to make a connection between them, between the letter "[she] was afraid to open" and the "letter [he's] afraid to mail," which trips a trigger in Oliver. In this moment he severs that connection, rejecting the notion he's afraid to mail the letter. Shane was brave enough to reveal her fears aloud. Unbeknownst to her, Oliver is expressing his fears as well.
It was "a certain clarity" Oliver experienced in the vault during The Treasure Box that prompted the words in Oliver's head (and maybe his heart?) to finally find expression on paper. By A Hope and A Future, several days have passed and apparently the letter has sat stamped and addressed in his desk drawer for some portion of that time. As per usual, it's Shane happening upon the letter that prompts Oliver to finally remove it from his desk. Shane once again acts as a catalyst, pushing him towards resolution.
Notice he doesn't offer much to the conversation as Shane pours her heart out. He only spurs her on with "because" to get an explanation for why she's sorry for looking up Holly at all. The opportunities Oliver is given to offer his side are met with deafening silence. Where Shane may have interpreted his silence as rejection, the countenance of Oliver's face reveal the fear he harbors. We can know it's fear because of the strong reaction he exhibits to Shane's suggestion he's afraid to mail the letter. He offers his first---and only---full sentence to the conversation. At the same time he leaves it open that there might be something of which he's afraid, which Shane challenges. And while Oliver's exit on this note seems shockingly abrupt, it's perhaps the first time Oliver has been confronted with the possibility there is something of which he might actually be afraid---and he has no idea what to do about it except flee, leaving the question unanswered, and Shane devastated in his wake.
The truth is, we know of what Oliver is afraid---what happens next. His House Rule revealed as much. In order to pursue, and ultimately achieve, the peace he so desperately sought, it would require Oliver to take risks---risks like sending his letter to Holly. This is the struggle we see play out in the pouring rain. Convicted by Ardis' words about "doing the thing that scares you the most," and prompted by discussion of what Norman was afraid of in the hospital room just prior to Oliver's exit, he gathers the courage to seek out a mailbox and send the letter.
It's hard to forget the sound of the mailbox shoot snapping shut. It's a defining moment for both Oliver and Shane, who we come to find has witnessed this monumental step Oliver has taken.
When Oliver drops the letter in the mailbox, the bit of armor double-padding his heart is gone, making him instantly more vulnerable. And you can see it all over his face, particularly when he turns to find Shane watching him. In this moment, both their fears of uncertainty are realized and mutually acknowledged through their facial expressions. It is officially out of both their hands, and each of them know it. The weathered and bewildered pair are left in a wordless, unresolved state as the installment comes to a close.
Over the course of the series, the conflict regarding Holly has lingered in the background, inching closer and closer to the fore until its resolution became an inevitability. The stakes at their highest, Shane and Oliver found themselves at a turning point, facing the same uncertainty---and even fear---about what would happen next.