If a guy cannot wear a condom lubricant or not. he is on hard before he puts the condom on then before he has inter course it goes limp what could be wrong?

Erectile dysfunction: If your guy can get erect (hard) enough to put on a condom but goes limp before intercourse, he still has erectile dysfunction but more likely related to performance anxiety. Make him go see his Family Doc for evaluation. Viagra (sildenafil) & its competitors might help if that's all it is. If not enough, we worry about venous leak which can be fixed by wearing cock ring to keep blood from leaking out.