Wtf happened??? Is this dropped ??
Here is the link
https://www.sublimemanga.com/world-s-greatest-first-love
You probably couldn't find it because it's not called Sekaiichi Hatsukoi. It goes by the English name The World's Greatest First Love. I recommend getting the physical copies off of rightstufanime.com because it's the cheapest. Amazon is probably the next cheapest place if the other site has a volume out of stock.
Spoilers ??