Scott apologising to Kim, basically for being himself, at the end of Volume 5. Kim's reply is a completely sincere "Apology accepted", actually smiling for a change.
Even sweeter in the movie: Scott just tells her he's sorry, and she responds wordlessly with the warmest smile.
Scott finally telling Ramona he loves her in volume 4. And her saying she loves him too afterwards. The event gets followed by this panel◊, which is equal parts endearing and awesome.
Near the beginning of Volume 6: "K-Kitty."
Scott's building anger when Todd slaps Knives.
Ramona reappearing to Scott after months of absence in volume 6 and trying to apologise to him for being such a sucky girlfriend, but she can't get it out because Scott just won't stop kissing her.
Scott: Damn it, Ramona! I forgive you already!
In volume 5, Ramona, Scott and Kim get smashed at a party, lay around in a pile on a bed upstairs and drunkenly pal around. Then when they finally leave, Kim pulls them both into a group hug before heading home.
Kim: I seriously wish I could...like...be you, Ramona. I mean, you're so...y'know?
Ramona: *kisses Kim on the head*
Though it doesn't make Scott feel much better, there's something very sweet about Knives telling him in volume 6 that even though she's moved on, she still cares about him.
In volume 3, Ramona and Envy are having a battle, and Ramona is getting verbally beaten down by the crowd while everyone cheers on Envy. Then Wallace shows up and yells "BREAK HER FACE, RAMONA! BREAK HER HORSEY OL' FACE!" This properly surprises Envy, giving Ramona an opportunity to catch Envy off-guard with her hammer.
Wallace then proceeded to be the only person to cheer Ramona on.
During the fight between the twins and Scott in Volume 5, Kim (from her cage of captivity) pretends to have received a text of encouragement from Ramona. This gives Scott the Heroic Second Wind he needs to defeat the twins.