"Let me carry you off while you say I should leave you alone. Whoops, we fell. What's wrong? Did you injure yourself?"
Ohga's so inquisitive immediately after messing up and potentially worsening Kariu's sprain. Like, at that point, the best thing to do is to leave her alone like she urges you to. You don't get up into someone's face after you've hurt them whether it's accidental or not, when they've made it clear they want you to leave them be, unless you want to hurt them.
I get that she's not mad merely at him. That there's a whole lot more going on. That she just wanted him to not notice that she was injured because of a warped sense of pride. But all the context Ohga has is that she wanted to be left alone, he went against those wishes and physically forced her up, only for that unstable setup to get them both to stagger and fall down unnaturally, leading to Kariu crying out in pain. The only thing that should be going through his mind is that he messed up and injured her.
For a supposed dense guy he somehow seems to see right through everything and inquires deeper instead. We get the 'heart-thumping' chivalric line of "guy can't leave crying girl be, it wrong" at the cost of common sense and character. Really forced, really disappointing.