I'm sorry you are having so much trouble. Sometimes I think the cognitive losses are one of the hardest symptoms to deal with.
Anyway, I say don't look for a partner, look for a friend. If something comes of it great but if nothing happens at least you have a lot of good friends that you can lean on. As far as rejection, well that happens to everyone at one time or another and if someone rejects you because of the MS then you don't want to be around them anyway.
I personally gave up on marriage and/or relationships but I'm 45 and I just don't have the energy to work at the give and take that is involved anymore. I'm ok with being single and alone.
Good luck and I hope you feel better soon.