Character Analysis
Where would Lennie be without Joe? He draws her out of her shell with his charm and positivity, he gets her to take up music again, and he becomes her reason for getting out of bed in the morning even though her sister is dead. Plus, he's super easy on the eyes. And grieving or not, who doesn't appreciate a little eye candy?
Mr. Jouissance
When someone thinks you're amazing, its hard for the feeling not to rub off on you. Joe's love for Lennie takes some of that companion pony mentality (which we discuss on her page in this section) away from her, and makes her think of herself as more of a heroine. If Toby represents sorrow and grief, Joe's definitely the bringer of joy in the book—fittingly, these two are compared to the moon and sun a lot.
For the most part, Joe's upbeat perspective is much needed, a bit of brightness in a generally bleak landscape. That said, though, there are moments when he doesn't seem to understand what Lennie's going through, and she needs to talk to someone else. Joe's good, but he's not a one-stop shop for all of Lennie's needs.
Fatal Flaw
Even if Joe is Lennie's soul mate, no love interest is perfect. Joe's fatal flaw is, to borrow Lennie's words, his "dickhead-his inability to forgive" (32.21). She's referring specifically to something Joe says to her on a date: "You're cool […] Forgiving. Unlike dickhead me" (23.60). Looks like Joe shares Lennie's assessment, then. Importantly, he says tells her this before he finds out she is cheating on him, making it crystal clear to readers that our main girl is headed for disaster in the romance department (since we know about Toby all along).
Sure enough, when Joe catches Lennie with Toby, he's not having it. While we understand that Lennie betrays Joe in a major way, though, he fails to take into account that Lennie's sister has just died. It's a pretty big complicating factor, particularly when you consider that the guy she's betraying Joe with is her sister's fiancé. Which leaves us with one question: Is Joe too married to his own idea of himself as unforgiving to assess the situation more objectively and maybe find a little forgiveness in his heart?
From Dolt to Ally
Fear not, the answer to our question is a resounding no, and in the end (spoiler alert), Joe forgives Lennie. It's not because she wears him down, either—instead, he learns more about her situation, and it helps him understand where she's coming from. As he tells her:
"I'm kind of an unforgiving doltwad, if you hadn't noticed. […] I don't know, reading all those poems together, I started to really imagine what you've been going through, how horrible it must be…" (37.21)
So it took reading Lennie's poems for Joe to really put himself in her place. He could've just listened to Lennie instead of going through the process of searching for all her poetry, but hey, no one's perfect. We're glad he's at least the kind of guy who can admit when he's been a doltwad, as well as someone who took the time to really think on Lennie and try to understand her instead of just casting her aside.