Hi MrsDE. I have my personal theory that in many cases where erections vanish quickly in men there might BASICALLY be an imbalance of cGMP and PDE5. In many older men with erection problems and unknown cause this might be case. The medicine business (yes, it is a business) has zero interest to find any reasons for it because they want continue to sell medication. Let him try Viagra or any of these medications as it might kind of normalize the cGMP/PDE5 ratio for a few hours. However, I don't think that the DE issue will be improved by this because the medication doesn't increase arousal which is mainly responsible to get to ejaculation. The fact that he can get harder by masturbating might also indicate a psychologically based issue (self-esteem ). Good luck!