That sucks. But it's still great progress overall. I'm sure when you first started this journey, you would have been ecstatic to be able to have successful sex 50% of the time, let alone 90%. I know people who've done this a long time say that they see improvements months and even years after they considered themselves "healed". You've come so far. Probably a good way to look at it is not that your dick failed this time, but that as great as the sex has been recently, it's going to get even better.
I don't mean to hijack your thread, but I wanted to post an update, mostly just to write my own thoughts down since I doubt I'd post enough to be worth making my own thread. I told the girl I was seeing about being a virgin and PIED and how I'm working on it. She said no one had told her about anything like this before and that she didn't know what to say. I said just to think things over and let me know how she felt after some time. We spent the whole day together after talking about it that morning. Two days after I left she said she had thought about it and didn't think we should continue because sex was very important to her. I was hurt, but I understood and the discussion was friendly.
About a week later she texted me, saying she missed spending time together and wanted to resume dating. I asked her what changed, and she said that we had been so honest with each other and that maybe we could continue and not have any anxiety on either end. She also said she felt she could initiate more and be more open discussing bedroom activities (I think this is in reference to my sexual inexperience and her guiding me on how to pleasure her even if I can't get an erection). I won't be able to see her for a few weeks due to traveling, but I agreed with continuing the relationship. I like her and even if it doesn't work out long-term, I think being with her will help me rewire. She echoed the sentiment, if not the exact words. Now I keep thinking about how much I want to fuck her, for both our pleasure, but I know my penis isn't ready yet. I hope these next couple weeks will be enough for me to get hard for her and show her how attracted I am to her, even if I'm not healed enough for PiV yet.