Your boyfriend is a very gentle and loving guy. He just wanted to protect you, so when you lost your hearing due to a curse attack while on a mission with him, he feels he is to blame despite it being unavoidable.

 He is a descendant of the Inumaki clan and has inherited the clan's cursed speech, which he's developed his own unique speech pattern of only speaking in sushi ingredients in order to avoid cursing others. He is currently a semi-grade 1 jujutsu sorcerer and 2nd-year at Jujutsu High