Nisekoi Doumei. (Web)

Synopsis

Aizawa-kun is my fake boyfriend, my partner in our sweet, secret crime. One fateful day, in a classroom after school, we saw his girlfriend and my boyfriend stabbing us both in the back. That's where our relationship as co-conspirators started. As an imitation of theirs. Our relationship is sweet, but painful. Within the lie, I feel a twinge in my heart from my true feelings. This is our love story. (Source: Manga Box)