Impossible bed dilemma— AIBU? Am I missing the solution?

Go to IKEA. They will have something suitable for sure. If your room is in the smaller side go with the double not the king size. We have a king size in my sons room and it has left it very tight to walk around.
also the headboard should be attached to the bed not the wall. Even so can a shower wall really be that flimsy? Our ensuit walk is very sturdy.

@lemonadecar
I used to buy beds and mattresses for a living.
Your mattress definitely could have been damaged by what you have described.

You should get the biggest bed that your room can take. If you are sharing a bed with someone regularly, the bigger the bed means that you both get higher quality sleep.

A vacuum packed rolled up memory foam mattress should easily get up the stairs.

it absolutely can

You could try the original bed company ( https://www.obc-uk.net/products/beds/iron?gl=18h58oqupMQ.._gs*MQ..&gclid=CjwKCAjwkaXUBhASEiwAZI3ds64Z-Vxq5hlmCwzMWpw0SP6AIuiQ7aYT4bUuCXW-zrWK4DX-pCnlBBoCT_0QAvD_BwE&gbraid=0AAAAADmRao-00IpPKgsN9CRIbSj1-EsSJ ) I have the 'paris', the head and foot board look as good as new after more than 15 years (I had to replace the frame a few months ago), but you could think about the 'tiffany', as it seems to have a slightly lower headboard. Staff seem very helpful if you want to speak to someone before purchasing.

I have similar but from the iron.bed company or similar. No squeaks etc and I assembled it myself.

No point buying a posh mattress but having a cheap squeaky frame.

If you’re going to invest money in anything, make it your bed (frame and mattress). Also what is cheap? I suggested Warren Evans and for the amount we paid I’d consider that excellent value.

Our mattress was about £800. My mum thought that was extortionate but it’s still going strong after a decade and is still the comfiest night’s sleep ever.

We spend half our lives in bed, might as well enjoy it.

Personally, I'd go cheaper frame and more expensive mattress.

I would also recommend IKEA. You can look on line and order on line too. I recently bought wardrobes from them and at each stage of the order I was asked if I wanted Taskrabbit to build them. I bought 3 double wardrobes and one single with drawers , shelves etc and it only cost £250 to have them fitted . I thought that was cheap for a job I was incapable of doing myself. Good luck with your hunt .

What is your budget?

I have this from IKEA and it's very sturdy. Fits an under bed storage box too.

https://www.ikea.com/gb/en/p/neiden-bed-frame-pine-luroey-s79248611/

I have a loft bedroom with a very small and twisty staircase and had no problems getting it up. I unpacked it downstairs and carried the bits up in groups.

It may have already been suggested but what about a quarter-split ottoman so it's in 4 parts to get up the stairs? Use a company that delivers to your room of choice. Some may completely put it together for you too.

Like this:
https://onlinebedstore.co.uk/products/quarter-split-end-lift-storage-ottoman-divan-base?variant=61434307707210

Yeah, I wouldn't risk a sprung one and there is no problem with the John Lewis slatted base ones as they come in small parts. BTW the slats are designed to fit in the retaining clips with a slight bend which stops them being totally rigid. You won't feel a bounce as such but they have some flexibility which is better than a rigid base.

Get one from here, they are great and come in narrow boxes. Easy to assemble as well. I’ve had 3 from them. Sturdy frames and really well made.
www.getlaidbeds.co.uk/?aa=uk&ci=21838012274&agi=170156870838&fii=&tii=kwd-48577730905&mt=e&nw=g&kw=get%20laid%20beds&pm=&tw_source=google&tw_adid=718251242341&tw_campaign=21838012274&tw_kwdid=kwd-48577730905&gad_source=1&gad_campaignid=21838012274&gbraid=0AAAAADwjBF-vfUB4Wkbx-RWJfLBIJIZ9Y&gclid=CjwKCAjwkaXUBhASEiwAZI3ds4_p8ZH_JZoMbK36SpJv7_cA9LMIOi1LZkr_BWAa226LcH90IxeKzRoCtzQQAvD_BwE

If there isn’t could you get a joiner to build a frame for the headboard that attaches to floor and ceiling rather than wall?

Why on earth would she do this when there are a million bed frames out there with headboards that are an integral part of them?

Rolled mattresses are very standard these days and very good quality. They are exactly what you need with your layout.

You should downsize to a double any way OP so I wouldn’t worry about whether or not the King one got damaged.

https://www.theguardian.com/thefilter/2025/feb/06/best-mattress?CMP=Share_iOSApp_Other

https://www.which.co.uk/reviews/mattresses/article/how-to-buy-the-best-mattress-atlAf8V9fiZN?utm_me=&source_code=911CRJ&utm_source=google&utm_medium=cpc&utm_content=generic_mattress&gclsrc=aw.ds&gad_source=1&gad_campaignid=21439694522&gbraid=0AAAAADoAS40iMUfzsuTTyIFzFxOyx-Vs8&gclid=CjwKCAjwkaXUBhASEiwAZI3dsx6wxgOlkf940BOdrltiITdcv2Z38jZMUcGwTgQHUdGLKgG97WgkfRoCSL0QAvD_BwEWhich? Mattress Guide

Warren Evans. Sturdy wooden beds. They’ll put it together upstairs for you. Then just get those storage cases from Ikea.

I have just bought an ottoman bed from Ikea. Boxes fit in my car and the headboard is in 2 parts so you could unpack downstairs if that is too tight. The headboard is sturdy I'd say and it took me about 4 hours to assemble on my own. Mine was a double but I doubt the king would be much bigger in piece size given how it was packed - so give you choices.

I have a super king and I’m single. No way would I sleep in a single bed, I haven’t done since I was a child
she also has a boyfriend so a single is not going to work

I have this, was flat pack and you can set the height on it. Very solid and I often lean against the headboard to read
https://www.obc-uk.net/products/beds/iron/solomon?size=50&colour=black&_gl=1ex8mbr_upMQ.._gs*MQ..&gclid=EAIaIQobChMIgaqfjqC0lgMVZqRQBh2reSmPEAAYAiAAEgIJTvD_BwE&gbraid=0AAAAADmRao-BXM6ZZWwvxbcPg3M-LtaQT

Is there any chance of changing the orientation of the bed so you are not against the flimsy wall? If there isn’t could you get a joiner to build a frame for the headboard that attaches to floor and ceiling rather than wall?
I would go for a double to maximise the feel of space as well as being able to have a decent sized bedside table.
Futon company do ones which are less bulky but have less storage space underneath. John Lewis will deliver and build but cannot perform miracles with a twisty staircase. A frame and mattress will be more manoeuvrable than a divan. Next do some nice ones which are more reasonable than makes like Ercol.
You need to think about your mattress too (if you are replacing this, a lot of the ones which roll or fold are foam/latex rather than sprung. It does make getting them in more straightforward but be sure it is what you want to sleep on. At least mattresses can be bent round corners a bit.

Yep.

If going for the double, keep the king sized duvet though. It really makes a difference.

Warren Evans will help you.

Another vote for ikea. I bought the one that @Vegandiva suggests only I got the girly swirly version which they don't do anymore. When I assembled it I was in my 60's with an iffy back and a duff knee and I got it upstairs and assembled on my own. their matteresses are good too and come vacuum packed, again I got it upstairs on my own, DO NOT open the mattress until its in the room you need it to be in. The wood and particles board beds are heavier and more difficult to put together.