You sound alot like my ex. TL:DR I'm seeing a concerning trend among multiple posters so I want to call out this might just be good ol mental illness at play, while your frustration and pain are valid your tone suggests you've already thought a good bit about how things stand between you two, where the pain is coming from, and what your next steps look like. I'm not looking to change your mind but simply share my story in a hope that it could improve a life anywhere.
I too was super successful, full of potential, tons of interests and lived a fairly active life, she was in the same boat and through her own hard work eventually made it in to law school. I worked two jobs to help support her financially and thought I was supporting her the best I could emotionally as well. I was happy to do it because even though I hadn't saved the money to propose it was something we'd both talked about and I had planned. When I arrived at a place where I was playing video games 6-8+ hours a day 2 things were happening: I was extremely depressed and I because I was high functioning I was also completely oblivious of my own depression. ( I still consider myself a gamer fwiw)
Depression can absolutely kill libido, and if he doesn't know he struggles with it things may just seem "normal" but the reality is if he is depressed and oblivious you're probably barely hanging on because the you're living with the pale shade of a man you love.
It took me 3 more years after we broke up before I came to terms with my own depression and brought it up with her in conversation one day(we were still on friendly terms.) We were friends for years before we dated she actually witnessed me go through a rather particularly bad bout of depression for about 6 months and recover to then "become" the man she fell in love with. She never recognized it as depression at the time and neither did I. When it happened again and lead to the end of our engagement and relationship we both missed all the signs and symptoms then too.
The day she told me she couldn't do it anymore and that she had been "emotionally moving on for the last 6 months" I had bragged to a co-worker about how perfect and strong our relationship was and we were both still happy and so in love etc you get the idea.
When I was healthy it was perfect, and when I wasn't, it wasn't. I began re-evaluating my past looking for depressive episodes and things just started to make sense. Once I was able to identify it and give it shape I was able to treat it and I'm in a much better place these days. But I made a mistake during this process and assumed that at some point she knew I was depressed for some reason. It's been years since that day and now I know that by mentioning my depression it in passing she did the same thing and re-evaluated our relationship and the big picture and at the end of the day it broke her heart all over. It had been some time since we'd last talked and she started almost aggressively reaching out, frantic voicemails asking for us to talk, texts etc. It was clear she wanted to talk in person but I had a new gf that was a bit possessive so I mostly ignored her. After a few weeks she stopped trying. She started dating a week after we broke up so thinking that she was capable of that knowing that I was depressed for months leading up to that point and she had turned into a monster in my mind at this point.
Another 2 years go by and I've been single for a good year at this point and she reached out again and we ended up talking about all of it, the frantic attempts were her wanting to apologize for everything. Her attempts at dating never led anywhere during those months leading up to me moving out and she regretted me ever leaving(she even called and balled her eyes out when I was able 600 miles out) for the first time since she had ended it all those months prior. When my behavior at the time was framed in the context of my depression it began eating her up inside for ending what we had and I mistakenly let her endure that for 2 years.
My advice is to have a little compassion if you decide to end things, consider mental illness may be the root at what's ruining an otherwise good thing before you do. And for God's sake if someone you ever loved is trying to frantically get in touch with you pick it up.