21 yr old.can always get an erection from porn and ocassionally get morning erections but can't get one for sex, doubt it's psychological coz no anxiety?

Psychological.: I do believe it is psychological because there does not seem to be a physiological problem. I recommend that you see a therapist that deals with sexual dysfunction.

Psychological: If you have spontaneous erections (at night or upon waking) and get erections via masturbation but not sex, then the problem is almost certainly psychological (whether or not you subjectively experience anxiety). You might have a discussion with your doctor and try viagra (sildenafil) or Cialis on a temporary basis, to see if it helps you get past the problem. If it persists, consider psychotherapy.