Hi there, Its good to know that you want to support your bro in need. Does he have any physical limitations that would require you to do basic care for him?(like bathing,washing,dressing etc.,)? and when you say MR how severe it is? all this plays a role in whether he can or not be happily married. Each and every woman has expectations from husband...If you are sure a girl would marry him for what he is and be happy with that,then y not? As far your partner to be is concerned,I would say it will be unfair to place too much demands on her.If your brother requires lot of help physically and needs someone to tend to him for almost everything,then what amount of time you both( hus and wife) will be able to devote to each other?what will happen to the time that you expect your wife to be to spend on your bro,when you have kids?And how much physically demanding taking care of your bro will be? If the girl,out of her love for you, decides to tie the knot and partake some of your responsibilities,then pls do ask all of these questions to yourself before deciding.Of course we always want to take care of our loved ones.If I were you,I would do that too. But at times we do have to face our limitations. you may also consider hiring specially trained personal (like nursing assistant) to help. Sometimes its better to do that because despite our best intentions to help and care for our loved ones,we may not do the thing that is needed the most. In the end it comes down to the level of understanding between you and your future partner.I would say good way to start is an open discussion with her on this. Good luck!