Some advice?

As much as you love him, he shouldn't be using you as his only output for his problems- you're his girlfriend, not his therapist.

Hi there. As someone in a long distance relationship where we BOTH have mental health problems, I know how it feels when either of us have off periods. Has he considered reaching out to his Uni for some support? As much as you love him, he shouldn't be using you as his only output for his problems- you're his girlfriend, not his therapist. As someone with depression too, I'd hate to think that I was placing the sole responsibility on my partner to make me happy when my mental health struggles (that's not to say you shouldn't provide ANY support- my partner is my biggest help but relying on him isn't healthy). If he's not receiving any, he needs some kind of mental health support from his Uni.

hiya
I massively agree with this quote as this therapist role can take a huge toll on your mental health as well... but at the same time make sure he knows that you’ve got his back no matter what. It can be difficult to maintain a LD relationship at times let alone with one person going through some permanent stuff. Idk if he’s a “sporty” type even if not exercise can help so much. Even if its only walks or small jogs. It really did help me out a lot. Try suggesting that to him ☺️ or even finding an expressive hobby (art, poetry and those sorts)
Good luck tho, I’m sure you two will make it work !!

I really agree with this but the problem is that he’s quite a pessimistic person even without depression, and when he has off periods his general mood is “this is how I am, I’m used to it and nothing can change it” so I know it’ll take a huge amount of effort for him to even consider it

He’s also the type of person to bottle things up and that caused issues in the past, so I’m aware that him even telling me he was feeling lonely was also quite a big step

It’s good that he’s making steps to be more open. It’ll take a lot of gentle encouragement and persuasion, but gradually overtime working him up to seeking help would be good. He doesn’t have to immediately, but for me I’d try to tell him it might be good just to try it in the future and help him through the process. He needs to know that even if he’s been this way for a long time, change IS possible if you’re willing to try and make it happen.

He shut me out completely the last time I suggested it though

It’s worth bringing up again in the light of him going through a lower period and being lonely. Of course you can’t force him to go, but it’s good to remind him reaching out for support is a good idea (even if you don’t think it’ll help- it’s worth trying at least once) and that you’re only suggesting it because you care about his happiness.

We had a conversation earlier and he told me to stop getting so worried about things neither of us could control, and that he didn’t need the help

I can’t help worrying - he needs a girlfriend closer to him because I can’t do anything really

I think he needs to know it's something he can work on controlling. Being depressed might be something long term, but it's not a life sentence of doom and gloom. He needs to want to change and, with your support, work on getting some kind of counselling.