He sounds a lot like me. I usually present with this image of constant positivity and strength even when my world is falling apart. It takes so much courage to let someone in and see the vulnerable parts of you. My last...person, I guess. Put me on a pedestal. Would always remark how flawless and perfect I was. And the truth is, no one is perfect. It's so uncomfortable when you're aware of all your weaknesses and flaws for someone to be like "You are absolutely perfect and can do no wrong."
When I am angry, I do pull back. But it's not because I don't want to work it out. I have a vicious, sometimes uncontrollable temper. And I know if I'm fighting with my partner and I'm angry, I am incapable of resolving anything while I'm mad. I'll just rant, make cutting comments and make things worse. So I will step back to cool off and calm down. I've had a lot of partners get really upset with me for doing this, but I do it because I want to come back calmly and be able to focus on resolving the issues instead of fighting and being mean. To me, it's a show of respect to them and myself, as well as showing how much I love them. I think leaving someone on silent for days though isn't productive. Sometimes I need 5 minutes, sometimes an hour. But will come back when I'm level-headed to discuss and work on it.
I feel like we all need reassurance sometimes. And if he doesn't feel like you're being needy, I would go with how he is feeling. If your need for reassurance isn't a problem for him, don't let it be a problem for you. Like you, I have the fight or flight response, and a lot of times I will run. I know how much courage it takes to stay and work on things when all you want to do is run away because you're scared. This guy sounds like a good guy. I've shared my past with someone once and their response was, "Well, you didn't need to tell me all that but thanks." I love that he said what he did. Hang in there. Take it a day at a time. Being with someone who can help you grow is a wonderful experience even if it does get uncomfortable. I think you can both get through this.