...Has happened multiple times.? So it happened the first time me and my girlfriend tried to have sex, She tries everything to get me hard and it works if she does oral but right after shes done and we try to have sex it goes away, if i can get hard do i have ED or am i just worrying about this too much since its happened before? I am 18 and i can get hard by just sitting there with her but when it comes to sex I struggle with it. We have had sex once and when it finally got in i was fine.