my cock never gets hard

Hello my loves, I would like you to give me your opinions, I started anal more or less in 2006, although I already played with my anus from time to time, it was not with penetration or in the way I started doing it. later. Well, what I want to ask you is that I have never been able to maintain an erection when I practice anal sex, I don't have erection problems, in fact when it should work it works, although I really almost never use it. but when I need to use it I have no problems, my cock is dead from the moment of anal cleaning, I immediately insert a plug, I put on the lingerie and all the magic happens, I explode with excitement, my heart beats and my libido makes me moan, but the erection never happens, I love it like this, having it flaccid until I come, but sometimes I would like to be hard when I play with my anus, I know that the pleasure I will feel will be different. . I can get an erection if I play with just my cock, as long as I don't have anything up my butt. but every time I go back to anal action my dick goes to sleep again, is this normal? Is it a condition of mine? or does it happen to you? I would like to get to sissygasm someday with my hard cock. Could it be that I'm only made to receive love in the ass and nothing else? I await your answers