Sometimes a partner can find it difficult to perform when the sexual energy doesn’t meet the level of his previous experiences with past partners. Perhaps try broaching the topic with your partner of trying new and creative ways of performing that she may not be used to doing.
Thank you for posting. Sometimes calling it erectile dysfunction or ED can be scary or make it seem like a whole new separate disease, but erectile dysfunction basically means one's erection isn't firm enough for vaginal penetration, or that your erections have been worsened in some ways from how they were previously. Perhaps others want to word that differently, but essentially that is what ED is. Instead of thinking of it as ED, you could think of how to possibly make your erections harder. In an "ideal" perfectly functioning erection, the erection should be maintained on its own. However, some people can not even maintain them with their hand on it, and vaginal intercourse is impossible. So if it is possible for you, then that is fantastic. If you want to make your erections harder, there may be ways to do that.