To be honest, this is a tricky question, because while I know of the Class S genre, and the numerous works that were directly or indirectly inspired by it, I haven’t actually read many stories that would fall under that category. This is partially because most of those works are still untranslated in English, and partially because I don’t really enjoy reading those types of stories outside of checking them out for their historical significance.
That being said, there are a couple of series yuri that have characters experience this kind of mentality of sapphic relationships being temporary. They are also criticize this mentality in their own way, much like Cocoon Entwined.
Bloom Into You by Nakatani Nio has Saeki Sayaka, one of the major characters in the series, experience this during her first romantic relationship with an upperclassman while she was in middle school. This gets covered in more detail in her spin-off light novel series.
The Moon on a Rainy Night by Kuzushiro has a secondary character describe her experience dating a classmate from an all-girls high school who wanted her to dress like a boy while going out.
She Loves to Cook, and She Loves to Eat by Sakaomi Yuzaki has a more indirect example of this, as Nomoto Yuki, one of the main characters, has a nightmare about her girl friends “growing up” and falling into society’s heteronormative expectations.
Hopefully that answers your question!
