Listen to me. I was you.
YOU are doing nothing wrong. There is nothing wrong with you. He is the one with a problem.
You are a healthy woman and you want to be intimate with your partner. You are comprensive and you tried to activelly fix this for years.
And I am sure you are beautiful too.
No more comprensive talk. There is an issue and it needs to be fixed so we go to the doc that fixes it.
The guy clearly can't deal with this problem himself so no more promises.
Get the number of a therapist make an appointment and tell the bf you two are going there. If he dares open his mouth look at him with a death glare. Then smile and leave.
It doesn't matter if he suddenly wants to have sex with you; do not cancel the therapy.
Take control of yourself back. You've got this.
Do not open the relationship.