"You sure about that? He's actually right in that she does spend actual time with her friends doing normal stuff, while when it's with him it's just for sex."
Did you read this manga backwards or something? It's HIM who only goes after her for sex, she says right in this chapter that she's not happy with being just a sex friend. It's right there, page 7.
Besides the teacher she's the only one who wants something MORE with him.
And yet she ultimately does nothing on that front. Even the president has tried more to "fix" him. She's been cowardly, reticent to lose what she has. She doesn't show signs of caring more about him than her own feelings. This is regardless of what she thinks she wants. Talk is cheap, "thoughts" are even cheaper.
Sure it's not like she's a "lover" in any overtly or comically degenerate way. Doesn't mean she doesn't have a problem. Like I said, the person closest to what she is so far is Kiyo. Whom Gotou only assumes wants something more from him actually, but hasn't really shown it.
And as I pointed out in another comment, I didnt say he was blameless either. But that's simply the practical reality. She's in love with an imaginary version of him, and the great thing about imaginary lovers is they're relatively maintenance free, easy to adapt to, easy to reframe in ones mind.
I know the series isn't exactly high brow but maybe if you want to call out people for not reading, you should read and think about it with a little more emotional intelligence than that of a rock.