Let me add that the only thing worse than having spent too many years masturbating a lot for getting used to cumming with another person, is if you have spent all those years masturbating always doing it the same way, in the same position, with the same fantasies, etc. Some of my partners over the years have had a really hard time cumming, with me or anyone else, because their body and mind were only used to one narrow routine, played over and over again.