I have not had this penis erectile problem, so I can't say what is best. I would recommend that your boyfriend seek the advice of a specialist, urologist doctor. He will best be able to help your boyfriend. It is my understanding that penial surgical correction by arterial and/or venous surgery can help, and that there are different techniques, but it requires a medical professional determination of which one is best for each individual.
I wish you both the best.

Poor & soft erections - Reply by: Admin
Erectile dysfunction that responds well to medication is usually related to psychological issues rather than arterial blood flow. When the response to either natural or stimulated arousal results in a poor and soft erection, or one which is quickly lost, the problem is more likely to be venous.
Vascular Disease is the leading cause. Vascular disorders including arteriosclerosis (hardening of the arteries), hypertension, hypercholestremia and other conditions which interfere with the blood flow to the penis. Additionally, "venous leakage" also contributes to poor erections. This condition occurs when the penile veins are unable to constrict efficiently during an erection. When these veins "leak" blood escapes to the periphery resulting in a poor erection.