I’m going to ask what maybe sound like some dumb questions, but I don’t know how MS affects you, as it affects everyone differently.
When you say you can’t walk, do you mean literally - not at all? I.e. need a wheelchair? Or do you mean you can, but it hurts, or can, but you get tired, or can, but you’re scared to, because now you’re diagnosed you fear physical exertion might harm you in some way? Or some other reason?
I’m just trying to work out whether your barriers are mostly physical - i.e. literally paralysed, or mostly psychological - i.e. paralysed from fear? Is the diagnosis the problem, or your current capabilities, or lack of them?
If your problems are physical, are you having any sort of rehabilitation, e.g. physiotherapy?
You don’t say what type of MS you are diagnosed with. If it was RRMS, there’s still hope of improvement, as relapses can take many months to recover from. If you were only diagnosed in March, it is too soon to conclude no further improvement is possible.
I’m interested you say you can’t write your diary. So possibly not hold a pen? Yet you can clearly either type or dictate into a computer using voice recognition, so why not keep a diary that way? Is it essential to have a paper, handwritten book? Or is capturing your thoughts the important part? In which case you could do it by any means possible.
A lot of people with MS do go to the gym, believe it or not. I’ll be honest that it’s not my thing - but then it never was when I was well. Obviously it would be sensible to have a word with them first, and not just turn up, but there may be equipment you can still use.
I have found I have been able to greatly extend my walking range with continued practice. I’m not suggesting this would work for everyone - e.g. if you’ve lost use of your legs completely. BUT, if you can still walk, but have lost range and stamina, it’s possible to build it up again.
When I had the relapse that led to my diagnosis in 2010, I avoided walking for quite some time, then found to my horror I was struggling to walk to the post office, just three minutes round the corner. That gave me the needed shock to realise that if I didn’t fight back, I was going to be housebound. From that point, I started making a conscious effort to walk just a little further than was comfortable, every day. Progress was very slow and disappointing at first, and I wondered whether I was doing more harm than good. But very gradually, my strength and stamina improved. I am now walking further than I routinely walked when I was well!
It’s NOT all plain sailing - in fact, only this week, I went on an organised walk for people with health problems, which went a bit wrong. Either the organisers had failed to walk the route a few days in advance, as they usually do, to check for any unforeseen obstacles, OR we took a wrong turn somewhere. But either way, it took us a lot longer than expected to get home again. and we had to climb over fences (supposed to be styles, but they were broken), fallen trees, and negotiate head-high thistles, nettles and brambles. I was not amused, and got home in a distressed state, and had to retire to bed for the rest of the day.
Nevertheless, when I was diagnosed, I could never have imagined being out climbing over fences and tree-stumps - something I never did when I was well. Even though it wasn’t exactly intended, I’ve done it this week - and lived to tell the tale.
So I would certainly encourage you to use and develop whatever capabilities you still have. Nothing improves from neglect. If you still have it, work to strengthen and improve it.
I can’t advise you about the bf thing, because I wasn’t in a relationship at diagnosis, and am still not now. It just seems he’s pretty invested in you, because he didn’t bail when serious illness reared its ugly head, so it would be a shame if you undermined his commitment, by deciding you’re not worth it. He evidently thinks differently. It has been said - not just to me on this forum, but others here - that it’s not for us to decide on someone else’s behalf whether we’re “worth” being with. That’s a decision only they can make. So far, he’s decided yes, so who are you to interfere? He’s a grown-up - he chooses what’s acceptable to him; you don’t. Everyone’s got something less than perfect about them, even if it’s not a horrid illness.
Only time will tell if your illness is going to be a serious issue in the relationship, or even the making of it! Sometimes people grow closer in adversity.
But it’s not yet six months since you were diagnosed. Far too soon to be making any irrevocable decisions.