"I'm turning her down."
If anything I'd give extra respect for Shouma's resolve. Logically speaking he'd probably be better off with another girl with the way he was being treated, but I like that he follows his heart with conviction. Shouma's a strong boy, he can take it. If he actually manages to win Marika's heart at the end of all this after she's become even a little bit of a nicer person, he deserves his win.
"You should treat him right too."
Pretty sure those words cut more deeply than it seemed. Truer words have never been said, from Sawa, the person she didn't want to hear it from. But yeah, this chapter is the kind of story development I've been expecting ever since Marika and Shouma "got together": her leaving her unrequited first love behind, getting her feelings sorted, and maybe, hopefully growing up and learning to be a better person.
"I feel no urge. No urge within me to cross that line."
People label her a lesbian, I still think she's bi because she's at least got sexual compatibility with Shouma, but these thoughts clearly show she's more sexually confused than anything and it's not really as clear cut as we'd like it to be.
I actually found some enjoyment in this chapter. I guess it helps that I don't hate Marika as a character and I find her and Shouma's relationship to be very interesting.