Then! I completed all the main events (Rosetta, Emma and Cindy). However, in the achievements it says there are still 2 events left. Also, I couldn't find card 51 (page 6, card 6 [column 3, row 2]). The gallery is all complete. If anyone has a list of all the events so I can check which one I skipped, I'd appreciate it. It also helps if anyone knows about the 51 card. To Dev, I leave here my thanks for contemplating us with the best waifu ever created, Marin.
EDIT: Following the information from fellow TARLA111, I got the last card. Just the two events that are still missing.
Viewing post in School Of Love: Clubs! comments
You literally have to go into the Boys WC when the tip indicates.
Spend time with Rosetta and when the hint says. Go to the School second floor, then right corridor, then entrance 1-C, and enter the Boys WC at evening. Remembering that Coyote Club needs to be at least level 3. When you enter the WC, the event will start.