First thing to do is read as many of the posts here as you can. This thread is by far the most complete source of info on RE on the internet and probably anywhere.
I'd start on this page and work backwards. The trick is to discover what is causing his RE. There are posts here that explain in detail all the causes of RE. Here it is in a condensed version:
RE is mainly a psychological problem caused by anxiety which in turn causes low levels of arousal. Both the anxiety and the low levels of arousal may not be recognized by the guy. He may not feel conciously anxious and may very well feel fully aroused so don't depend on him to be able to explain what's going on. In fact many guys blame the partner because they just don't understand why it is happening.
There are some non psychological causes too- some drugs such as SSRI anti depressants, blood pressure medications, illegal drugs and alchohol can retard ejaculation. Usually the problem stops when the medication or drug use is stopped. They are some combination therapies for those who have to take medications and these usually involve taking the drug Wellbutrin with the other, RE causing drugs. Wellbutrin in many cases cancels out the RE effects of some drugs.
Porn and RE can be connected but porn can also help cure RE.
In the first case, chronic porn users/masturbators get conditioned to only being able to get aroused enough to ejaculate this one way. On the other hand in cases of RE caused by performance anxiety, porn can help distract the man and take his mind off the performance aspects of intercourse. Porn running on a TV in the bedroom has proved very effective in helping some men with RE ejaculate inside the vagina.
Lack of attraction to the partner is common mostly in long term relationships where the physical aspects of the partner's sexual desirability are no longer apparent to the RE sufferer. The visual aspect of sex being the primary arousal focus of men. Again, levels of arousal never reach the orgasmic threshold.
Sex therapy can help but its benefits in cases of severe RE are questionable. A better approach is therapy to get to the root of the man's anxiety whether it be just sexual or a more generalized anxiety disorder.
Beware the false info out there about RE. Causes like the man being circumsized, strict religious upbringing, a subconcious hatred of women or the purposeful holding back of orgasm to punish the partner is mostly outdated gibberish from the 1960's.
If you can't find the info you are looking for on this site try this one:
http://www.fertilitext.org/ubb/Forum4/HTML/000029.html