You are right to be concerned about the
blood in your boyfriend’s sputum.
Coughing up
blood is definitely abnormal, under any circumstance. Given his age and long smoking history, the blood was probably due to his having chronic bronchitis. If so, that would be serious now and, even more so, later in life. This blood should be considered serious and, at a minimum, he should see his doctor and have a chest x-ray.