i think the gist was each part was the same story told from the perspective of each girl. and in the second part you learn that the smaller girl who the taller girl was in love with and was afraid was being a bad girlfriend to ended up actually having been a covert pervert the whole time and was just unable to express her physical desire to her girlfriend. I think one of the major points was how the smaller girl passes out for a bit before the emotional climax and the taller girl thinks she's been sick and trying to be polite about it when in reality the smaller girl just got a nosebleed or something.

Is it Midsummer Pure Love and Midsummer Beast by Kida Miyuki?

Yes! thank you

For future reference there is actually a thread that can be used for these kind of requests. https://dynasty-scans.com/forum/topics/11660-what-s-that-manga-called