is it unreasonable to ask for a break when you live together?

i assume she's under 18? some private doctors will still prescribe them. but tbh, they are so hit and miss. i've been on so many different ones, usually they just numb you. at this point, i'm kinda over the whole thing. i'm starting to feel like everything they say about depression is bs, and it's usually just due to past trauma and/or general dissatisfaction with life

No she's 19.
She was 18 when she went to talk to the GP about it. Dunno what was said specifically as I wasn't there, but she said they wanted her on Talking Therapy rather than pills.
I still think a solo holiday leaving your everyday life behind for a couple of weeks could be therapeutic for you.

he's so angry about it and doesn’t want to hear it. he says that if that’s what i want, i should just move out, even though he knows that's not an option right now

1) I would never allow a girlfriend to dictate that we were on a break, she’s with me or she’s not and your boyfriend homosexual or not is correct in his reply here.
2) If your not committed to him then he has no obligation to you and I’d definitely boot you out were I him if you broke up with him.

What do you think it would take to unwreck your brain? Or to take away the feeling that your brain is wrecked?

i just want a break from everything, i'm not in the mood to ******* entertain him whenever he feels like it because my brain literally feels wrecked right now, lol. i don't see why that is so wrong

Go ahead and do it. See how you get on. Trying to do something to sort your head out is better than doing nothing. Even it doesn't work out. At least you tried.
If you think you'd get more peace and quiet by getting out of your shared home for a while; do that. Leave him a tear-jerking note along the lines of "I love you very much. Right now I can't demonstrate the love that I feel for you because I feel like my brain is wrecked. So I've gone to a monk-like retreat for a while to try to sort myself out. Don't worry. I'll be back!"

Wishing to take a break from your relationship is problematic.
You should tell him to AirBnB a cabin in the Lake District for a weekend for you both to be away from the world without damaging the relationship.

I was going to say I've been looking at this thing for my daughter (who suffers from depression) but I haven't quite decided whether or not to get her one yet.
I wondered if it might be of any interest to you:
https://www.flowneuroscience.com/

i don't see how being mentally drained, wanting a break from 'relationship duties,' and trying to avoid conflict is problematic, but okay..

i don't see how being mentally drained, wanting a break from 'relationship duties,' and trying to avoid conflict is problematic, but okay..

Well yours is a bad example because you have a horrid dynamic but in a healthy relationship, you should separate the family from the world. If you want a relationship break then that signifies larger issues.
It goes without saying but one of the defining qualities of being in a relationship is that you are committed to said person. Commitment cannot and should not be an on-off.

Horrid dynamic?
In some ways Ciel and his boyfriend have the strongest and most beautiful relationship I've ever come across.
The way they've always made up with each other after falling out.
And yes it IS fine if the commitment waxes and wanes within a relationship.
In terms of the time each person spends with each other.
Especially in the context of Ciel feeling like his brain is wrecked. So that fixing that or mitigating it should take highest priority above everything else in his life, with his boyfriend giving it a high priority too, if he's thinking straight, which he wasn't when Ciel first raised the idea of taking a break.
This is the real world, not some Disney movie.

In the real world, relationship breaks are just a slow car crash. They very rarely signal that the relationship will bear fruit (i.e. marriage).

As has been mentioned, wanting to end things, which is how this would likely be interpreted, will be a problem for a lot of people?
Push comes to shove you want space but you don't have any and you aren't really willing to do the things to get your own, so you're trying to create your 'space' inside the actual space of the person you want space from... It's just not going to work out that way without causing quite a lot of resentment towards you.

Well yours is a bad example because you have a horrid dynamic but in a healthy relationship, you should separate the family from the world. If you want a relationship break then that signifies larger issues.
It goes without saying but one of the defining qualities of being in a relationship is that you are committed to said person. Commitment cannot and should not be an on-off.

you keep talking about commitment, but it’s not like I’m planning to date anyone else in the meantime. i just want a break from everything, especially the physical aspect of our relationship. that doesn’t mean i want to be involved in that way with anyone else tho

See the problem is that he doesn't believe that or doesn't trust you not to even if not intentional from the outset. I don't entirely disagree.
If you have a married relative to stay with that may comfort him albeit you wouldn't get your 100% space.
This is an instance where the compromise may have to be space from the world but not him (cabin in the woods) or a reduced cut off from the world to stay with somebody he trusts (your considerably less likely to go out and do something if with a parent or married relative).