This arc has a lot to do with Misuzu being unable to admit her feelings to herself. Whether about Jun, Tomo, Carol, or herself. She's trying to convince herself that she's okay with what's happening when she's clearly not and she's upset that Jun is the person coming forward to try to alleviate it, since she prefers to think of him as useless. Here, she's just trying to deflect but she's getting close to a breaking point, making up blatant lies.