You're right, it might just be a fundamental incompatibility! I've left it out in my post but in the earlier days of our relationship he was very thoughtful and often let me know he was thinking of me. Since then it's ebbed away. I've brought it up before, and he said 'it's not like our relationship dies every minute I don't talk to you'. But it's not like I'm asking him to talk to me every minute of every day. I'm a busy person too and I give him a lot of space. I think maybe the levels of space we're comfortable with are very different. It's strange because in the beginning he was the 'clingier' one, which is why I make sure to plan my activities around time for him. We've talked about the level of involvement and he says he wants to know about my day to day and wants to be there for me, but in practice he's hardly ever there.

Re: your second point, I've struggled with depression and anxiety in the past and a lot of therapy has helped me deal with that really well. I feel pretty mentally healthy on a daily basis now which is why the prospect of it all being a farce and me actually being codependent is really scary for me - hence this post! I told him before that that I was upset and wanted to vent a little, but he still opted for work and sleep, which is his right! Prior to this relationship I have always been able to rely on myself or friends, but he felt like it was an unequal share of emotional vulnerability (he vents to me frequently, but I am a bit more reserved) so I've been trying to make an effort to share more. We've also talked about how I want to be a bit more prioritised, but he said he's working on it, and I'm not seeing much so far.