Cannot fuck; dick is limp

Why is it that when I try to have sex with a girl, my dick always goes limp? I can masturbate just fine, even to 3D (not actual porn though). I hate this shit. Why does this shit always happen to me? Why must I be sexually divergent? I just want to have some fun. I am tired of anime and video games; I want to get a life, but it seems "normal" life is not suited for me, despite me appearing "normal" to everyone else. Do I just have to let a train run over me and see what happens? It seems inevitable now.

>>1,6

Same here OP. I always end up with submissive girls who want to be tied up, slapped, called whores and have simulated rapes thrust upon them. When really all I want is to lick their feet and arseholes and let them pin me down and fuck me on top, while telling me they love me.