Believe it or not, worrying about whether you're going to stay erect can guarantee that you won't. When a man with an erection is threatened, the resulting surge of adrenaline almost immediately makes him flaccid. Unfortunately, the same reaction occurs when the threat is not physical but emotional. Anxiety about performance can trigger a surge of adrenaline. Presto, no erection.
Performance anxiety is exceedingly common.
Likewise, problems in a relationship or even job stress can cause the body to overproduce erection-snuffing chemicals. It's simply not possible to separate the biological side from the emotional side. That's why counseling should be part of the treatment for every man with erectile dysfunction. There's no sense working on a penis as if it's not attached to a whole man who has fears, emotions, and worries. I'm not talking about psychoanalysis.