Boyfriend, 22, not able to keep an erection. HELP!!!

I've been with my boyfriend for two years and our sex isn't horrible, but it a lot of the time is unsatisfying. He is 22 years old, mildly overweight, drinks moderately and smokes. He has had a past of some drug usage (weed, pharmacuticals), but has stopped. The problem is that he can barely keep an erection during sex and even when he's only consumed one alcoholic drink he cannot even get an erection.

On the off occasion that he can maintain an erection he only lasts during sex for at most 7 minutes, even when we change positions frequently.

It is so hard on both of us, because he is so discouraged for not being able to satisfy me sexually, as well as I am discouraged because I cannot arouse him enough to get an erection.

What could be the problem?
Please help...

[Dalubaba]

I have posted kegel exercises in this site in many posings.It can help. or search kegel exercises in yahoo.both of you can do this exercise and your problem is solved
you may also read Acupunture without needles by J.V Cerney page no.200 onwards.both of you can take advantage of these exercises.I it is a question of legth of penis  her is the device which can help to lengthen the penis.
The success of Phallosan is based on the principle of gentle stretching with the aid of vacuum. When worn, the device exerts an even, mechanical pull on the penis.This constant, painless expansion actually pulls the penis out of the body. As in body building, microscopic fibre ruptures occur, into which the body inserts new cell material. This makes the penis longer – particularly the head becomes more prominent – but not thinner.
Even with daily use of as little as 3-4 hours (preferably longer), the result will be visible in a matter of weeks. Following the adjustment period, we recommend extending daily wear up to 8 hours. The degree of success will be increases accordingly. In the preliminary series, Phallosan was worn without a problem for up to 12 hours per day with only short breaks! As far as we have been able to ascertain, up until now no other device worldwide has been able to achieve the same results without any pain. ON the following pages, we would like to familiarise you with the phallosan to ensure that you share in the success. The success of Phallosan is based on the principle of gentle stretching with the aid of vacuum. When worn, the device exerts an even, mechanical pull on the penis.This constant, painless expansion actually pulls the penis out of the body. As in body building, microscopic fibre ruptures occur, into which the body inserts new cell material. This makes the penis longer – particularly the head becomes more prominent – but not thinner.
Pleas note the length of the penis is not big issue as minimum erected length is 11 to 12 centimeters.2 inch depth of vagina is erotic so lenthier penis is not required..

[SixStringer]

For what it's worth, a group of sex counselors got together and decided that good sex lasts from 7 to 13 minutes.  Anything longer than that is carrying things on too long, and the quality goes down hill.  You can probably find this study somewhere on the Internet, if interested.  Of course, your boyfriend should quit smoking, exercise, and eat healthy, as many of us should, for his general health.  However, you might want to try something other than p-v intercourse if it is not working for either of you.  Is he ever satisfied sexually?  How long would it take for you to be satisfied, in general, if he were able to keep an erection?  If he would go the oral route, would that satisfy you?  These are questions to ask yourself to help you arrive at a solution.