Hi I am looking for a manga in which the protagonist (girl) is in love with the protagonist (guy), and they are friends, but he is with a girlfriend. When the guy breaks up with the girlfriend the friend decides to act as a substitute for the girlfriend only during sex. And she covers her unrequited feelings by telling him that she is in love with someone but that their relationship will never go anywhere. After a while the guy starts to fall for the girl, just when the girl decides to start dating someone else. At the end of the manga their friends, and themselves, are playing a game where the person next to them is going to say whatever the person wrote. Turns out she wrote a word that when repeated rapidly many times sounded like, I love you. In the end they end up together.
Thank you for helping me.

Sounds like Kare wa Tomodachi.

Favorite Shoujo mangaka:
TAKANO Ichigo
Robiko
IKETANI Rikako
ASHIHARA Hinako
YOSHINAGA Yuu
AOKI Kotomi

Favorite Shoujo Scanlation Group:
Forbidden Garden

Sorry but that one is not it 😔 , I remember it being shorter than that. It was like two or three chapters maximum. Thank you for your time though. 🙂