I don't get spontaneous erections or morning erections, or middle of the night erections when i wake up. i can get a erection when i masturbate. but never with a partner and fail to do intercourse. is this most likely psychological or physical ed?

If you can get erection with masturbation, you do not have physical ED. When you do masturbation frequently, morning erection or spontaneous erection may not occur. I wonder if you can't get an erection with just one partner or all of them. I think you need counsel from a sex therapist. Good luck.

You need to see a Urologist or a sex therapist. At your age chances are it is not physical. Good luck