I don't know Vjk... I have a #4, or at least I think I know my reason.
1) I've tried limiting myself to 2-3 drinks and get the same out of it. 2) I'm an atheist. 3) different room didn't help.
I'm great for blow jobs, but as soon as intercourse comes up, I lose it. At least the first time, 2nd time I've usually been able to keep it up for intercourse as well. Unfortunately, we haven't seen anyone more than that yet. I think it's a combination of not getting to know the woman enough, and some deep issue involving loving my wife and some inability to separate love and sex completely. I'm working on both.