skipping fast

Dear scholars, As-Salamu `alaykumMy husband has been muslim for 8 years and we have been married for 5 years now. Since we are married my husband has never done fasting completely when he was at work. He has always found that fasting giving him a hard time.however, He did do fasting all day when he was at home and half days when he was at work. Now, he works from 6 pm to 6 am and he breaks his fasting just before going to work as he said he can?t do fasting while working as his job involved in lifting and packing for 12 hours. He also has condition where his sugar level is so low and if he doesn?t have enough sugar in his body he could get collapsed. I do try to understand but sometimes I just can?t deal with the fact that most of the time he doesn?t do fasting. I just feel it is not  right because I have to prepare his food before going to work while I am fasting. However, when we were in my country during ramadhan two years ago he did fasting all day. What should I do ? why does he always find fasting giving him a hard time? for your information, islam is his chosen religion ( before he was catholic) and he has been muslim two years before we met.Can you tell me if it permissible in Islam not to do fasting in the certain conditions ? and ho w to make it up again someday ? do you have to do fasting or just pay money or feed the poor ? I look forward to receiving your answer as this issue often lead us to arguments.wassalam Magnolia