On the Ruka x Sugita thing, I reckon she just never consciously realised or admitted it, cause she was too bro-con style obsessed with her cousin to notice she liked his friend too & just took for granted he'd always be there too. I mean, they met pre-puberty or right at the start of it, so she'd already had this loving her cousin thing in her head before she met Sugita, before any real sexual attractions developed. So I reckon she's probs been moist for Sugita the whole time but in denial about it cause she's "supposed to love Ryou-nii". The writing for him and Senko has been on the wall since day one, so if she was really serious about her cousin she should have done something about it fifty odd chapters ago at the latest. I reckon the whole dick obsession and "Big Mountain" shit is her true feelings leaking out, especially when she's drunk. Sucks for Risa and she is objectively a better girl in basically every way possible, but obviously he loves the second most weird perverted chick in this story, and has for ages, so him choosing Risa now wouldn't be fair to her anyway, she deserves better than some dude that wants to bang her friend, right?