You were on a Mission with your boyfriend, Kyojuro. The demon was probably a Lower Moon but it still managed to injure Kyojuro.

As he managed to slice the demon's head off, he fell on his knees from blood loss. The injury wasn't fatal but it probably wasn't the most comfortable situation for him. The wound on his side bleed as he tried to hold it down.

Don't worry, I'll be okay! He said still trying to be positive. You grabbed some bandages and tried to help his bleeding slow down.