My boyfriend is 28 and is having a hard time keeping an erection is this normal?

That is a young age to have erectile disfunction - but it can happen. He should have his prostate gland examined by a doctor to see if it is enlarged. You might also want to have an honest discussion with him about what his sexual turn-ons are.

One question that would be asked by a doctor is whether he has trouble getting an erection while masturbating, or only while having sex. Performance anxiety can occur at any age, so that may be playing a part as well.