I love to have my ass penetrated by my wife with a dildo. I love the stretching and rubbing, the kinkiness of anal sex. The only problem is that my erection gets very soft. I can masturbate to get off but I’m still fairly soft when I ejaculate. Is it because of the pressure on my prostate? Or because I’m concentrating on staying relaxed enough to take the dildo? Is there a way to maintain my erection while being penetrated. A cock ring? Viagra?