He's 18 and it will either go soft after we've switched positions or while we're having sex. He said that it has never happened before. But I don't know. And also I takes so much to even get him hard. Foreplay doesn't, oral doesn't. Just like rubbing it. I've never had this problem with a guy before, all I would have to do is lay on the bed like I am ready for it and they'd be hard. But this one is a challenge. I don't understand.

How old are you?

Does he or has he ever complained of pain down there during sex of rubbing? He could sustained an injury during sex. Is he Circumcised? Some people say a little bit sensation is lost when the foreskin is removed.

What could be is when you change position he loses concentration. And since he’s only 18 yrs old, by the way how old are you? Maybe he is nervous if you lay around so much he doesn’t want to catch STD.

OP'er... so he is 18. How old are you? Its helps us address this.

I wonder if anything has changed since April when the question was asked.