Furuya-Sensei Wa An-Chan No Mono

From Chibi Manga:
I died when I was proposed to in a cafe, and I cried in front of everyone. But the person who proposed to me hasn’t even kissed me, I didn’t even know he was my boyfriend. This is the cruel Furuya-sensei (but he’s really handsome) that has an unexpected side, and An has fallen in love! Desperately trying to approach him, even with his guard up..?! A exciting and forbidden comedy!