Honestly, anyone saying that Kotooka is being "selfish" is just plain wrong, and objectively so. She's misguided, definitely, but not selfish. Nothing she's ever done has been for her own sake. In fact, it's almost always been detrimental to it. Her wanting herself and her friends to be "normal" is just straight up a Japanese self-sacrificial stereotype at this point. She's convinced that the road to happiness for herself and her friends is for them to be normal in society's eyes. She's like a parent who is convinced that they know what's best for their child, even when it goes against the child's own wants and preferences. Everyone thinks that their way is the best way.
Honestly, this whole love triangle seems like a friggin' paradox at this point; if one of them gets what they want, then the others end up miserable. If none of them end up getting what they want, then they end up miserable. Or, as Kootoka seems to think; if none of them gets what they want, then they'll all be miserable together for a while, but at least they'll manage to keep a little happiness in the form of their friendship. Like I said, misguided as fuck, but in no way selfish.