BF (35M) just told me he can’t afford rent. What do I (30F) do?

Sorry for this novel - might end up cross posting to r/offmychest.

Background:
We’ve been dating for 4 years, living together for about 3.5.

I work in a very high powered field that I spent the bulk of my 20’s training and schooling for. This was my struggle era: I was working on top of studies or low paying internships to have spending money and cutting costs wherever I could. I make a pretty comfortable salary now and am in the phase of my life where I’m finally not pinching pennies and am ready to start enjoying life.

He works largely in the service industry. When we first started dating, he moved out to live with me pretty quickly and spent our first year together bouncing around a couple jobs/unemployment. This was an orange-red flag to me and I had to basically sit him down and tell him to get his act together. He listened and has since been working in the same place for several years now. It took a long time but he is starting to climb the ladder and is being groomed for a management position soon. I have never had a problem with the disparity in what we do and bring home, but HE has constantly brought up that he’s ashamed of his career and has been cycling through exit plans for years now that have not panned out.

We live in one of the most expensive cities in the country. He makes a very reasonable Average wage, but he’s well below the poverty line in this context. I make approximately triple his salary. We started here for my training but don’t really have to stay: we both like our jobs and the area but an argument could be made that it’s not worth the cost. When he moved in, I made an arrangement that we would split major costs proportional to our income: I pay 2/3 of rent and he pays 1/3. he sold his car and shares mine, I cover insurance on that car (it’s paid off) and most utilities. He pays for the internet. We run our other costs like gas, groceries, whatever loosely 50/50: we do a “you get the next one” system and I don’t track that closely.

At first, this worked fine. More recently, finances have been a slow burning strain on our relationship. Part of our initial breakdown was that he would carry more of the responsibilities around the apartment, especially since I work more hours and it’s hard active work. I feel like it’s devolved into him giving me shit for not doing my part. I also have started to grow resentful at how much I financially manage in the background without even asking him to contribute because we have such a disparity in earnings. I was raised by immigrants and am pretty cost conservative: keep the thermostat down, buy groceries on sale, whatever. He seems to have no concept of this at all: he has a taste for the finer things and wants me to have what I deserve which I appreciate, but a lot of that turns into buying needlessly expensive basics/groceries and splurging on totally unnecessary things both big (coming home from Best Buy with a second monitor totally at random) and small (buying coffees all the time when we own an espresso maker).

We’ve had some spats here and there about our money arrangement and some challenges with him struggling to afford some of my friends’ social invitations and have been due for a sit down conversation, but nothing huge has come up recently. Today, out of nowhere, he came home and started sobbing that he didn’t have enough money to pay his share of rent.

I have no idea what to do. I have no idea how he got into this position.

Inb4 leave him: he’s my best friend of many years and the most connected and trusted I’ve ever felt with another person. I feel awful for him because I’ve been in a position where moneys been tight and I know how crushing and exhausting it is. He clearly feels terrible and was saying how worthless he feels and how ashamed I must be of him and it was really heartbreaking to hear. But we’ve also been dating for 4 years, we’re both over 30, he just turned 35, and I am really worried about his money management as I’m thinking about our/my future. I am a micromanager and I have an instinct to just go through his finances myself that I’m trying to fight because I really do need him to prove he has the skills. My first thought is to give him some time to figure things out, but I can’t figure out how much time to give or what I need to see him do to prove he can be a long-term financially responsible partner. He’s the first partner I’ve lived with and managed finances with so I also feel like I have no idea what I’m doing and am feeling worried that I set us up for failure in this space.

Help?????????