Most Helpful Guy
If you have to reconsider your choice of being his girlfriend then do you really love him? It's okay to be shocked that his physically fragile, I would too even though I don't even know him. It's a normal reaction to be shocked at something you don't see everyday. Not every male is born strong. Some had histories that make us emotionally and physically strong or weak. Find out why he is fragile, could be his past or medical problems. Maybe then you can understand what to do.
Most Helpful Girl
Honestly you may end up resenting him. That sounds like bitch like behavior, not masculine at all.
It is not your job to take care of any man, whether it be emotionally or physically.