Fearful avoidant partner created a version of myself that's wrong. How can I rectify it?

My partner is a fearful avoidant. He grew up in the foster care system, parents neglect, abusive relationships.

I'm the first partner he doesn't have to save, as I have my life in order and I'm emotionally secure.

However, I believe he's so used to chaos that stability freaks him out.

I'm good at communicating, I'm helpful while remaining my own person.

After months of dating, my partner has started being distant. A situation happened at work and he felt like a failure. Personal problems. Money problems.. A lot happened in a short time. He's been affected by it.

I remained consistent in my affection and told him I'm not going anywhere.

He's been more insecure and needing more space. Which I respected while still checking and being present. He barely leaves the house now.

Last week he told me he was depressed. I offered my help and support, however attempts to talk are met with passive aggressive comments or being pushed away. He thinks I'm needy, too demanding, he will nitpick everything I say. Why did you do that? Why did you say it like that? I feel like I can't win.

I understand his need for space comes from childhood. Isolation is where he feels safer. But ad a partner I feel like I deserve to be somewhat included.

The major issue is that he sees me as someone who lied to him about loving him, wanting to be with him. He thinks he's a failure and let people down.

I don't agree at all. But he feels that way regardless of what I say.

What can I do to be a better partner?