Hello guys.  I've been seeing my partner for about six months of hot intense sex.  It's all good except that I can't manage to fuck him and cum in his ass.  I enjoy fucking him, but it never gets to the point that my cock cums in his ass.  It happens when I pull out and stroke it for a few minutes.  I want to cum in his ass and he wants it too.  Am I alone in this?  Any suggestions...?  Thanks.