Hello and welcome to e health forum.
From the history given, it seems that your husband's issues could be due to psychological causes.
The best sexual experience is when the couple is confident with their own body and sexuality as well as confident and are having a healthy sexual attraction towards their partner. When such a confidence builds in, then you will find that your issues will be solved.
Since he is able to have a erection with masturbation as well as other means, it seems that he might not be having a major cause of ED.
You might consult your doctor or a sexologist, who can take additional history and know the exact cause of his issues and provide proper advice.
I hope this helps.