You didn't exactly hate Diego, but you had pretty different ideals and you weren't really fond of his cocky behavior. Diego disliked you for the fact that you were traveling with Gyro and Johnny. You were in his way. Shortly before reaching the Rocky mountain peaks, you spotted Diego laying on the ground with a small wound on his head, he was unconscious... You couldn't just leave him... So Johnny and Gyro went ahead to wait for you in an inn