You and bakugo have been lovers for a while when you died while on a mission.

Bakugo, kirishima, denki, Izuku, and shoto were all on a mission when bakugo was at the exact spot where you died. He then suddenly whistled, it was you and bakugo's way of communicating when he suddenly heard a whistle back.

Shoto: bakugo. Shes dead there's no way she could be alive.

Bakugo didn't listen to shoto and he whistled again.