Others have asked similar questions, so my answer will be the same. First, masturbation will not cause ED. The only way it could possibly affect your performance with a partner is if you had ejaculated shortly before engaging in sex & your refectory period wasn’t long enough to allow you to become aroused again - but that would only be a temporary effect. Masturbation will not weaken any muscles, nerves or blood flow that affects erections. In fact, frequent ‘use’ of your sexual apparatus would tend to keep it in good working order.
As for ejaculating too quickly, it’s common for many guys to get in the habit of masturbating very quickly & end up ‘training’ themselves to get off too fast. Sexual experts recommend practicing prolonging your masturbation sessions in order to allow you to hold off ejaculation. When masturbating, as you feel yourself getting close to ejaculstion, stop, take a few breaths, allow the excitement to diminish, then resume. Then when you start getting close again, as before, stop & wait for the feeling to diminish. If you can do this for several minutes, then at some point it’s OK to go ahead & finish - in fact, it’s not a good idea to get close to orgasm several times & then not finish - that can cause congestion of the prostate & leave you feeling very uncomfortable. But if you can learn to extend your masturbation sessions this way, over time you can hold off ejaculation for quite a long time. One additional benefit of this is that when you finally do ejaculate, it will most likely be a stronger sensation, more powerful orgasm & probably your ejaculate volume will be greater. Try this technique - I think you’ll benefit from it. In any case, it most certainly won’t harm you...