lasting

Ok so we are having a little difficulty in the bedroom. It's not that he has a problem getting ready or anything he just has an issue with lasting longer. Is this happening or happened to anyone else. He feels bad because he doesn't last as long but I try and reassure him that it's fine (actually fine not the fine we use when we're upset) and that I still enjoy myself. We've tryed a few things but it doesn't seem to be working. Would greatly appreciate any input given.