Impotence & Erectile Dysfunction Support Group
Erectile dysfunction or impotence is a sexual dysfunction characterized by the inability to develop or maintain an erection of the penis for satisfactory sexual intercourse regardless of the capability of ejaculation. There are various underlying causes, such as diabetes, many of which are medically reversible. The causes may be physiological or psychological.

His could be psychological if he's having difficulty with a orgasm. Has he been laying off the porn? Get him off of it.
What really helped me a long time ago is reading erotica. A girl and I would read 'My Secret Garden' together and then act it out. That alone made me a much better lover.