You have all touched on exactly what I was worried about. For me, it is not a matter of dysfunction per se, i its that anxiety thing again. We have swung with 3 couples and a couple of single guys and a few times even though I was excited the worries popped up. I was able to get through it each time and perform as I wanted to but I do worry about it. When I have taken Viagra with my wife, I just seem to go on as long as I want to, and worries or not I stay rock hard.
Thanks for your concern.