My mom did for several years.  My grandmother had dementia and it was very difficult for both of them.  Feelings got hurt on both sides because it was hard for both of them to accept.  Mom finally reached out for help, and they brought in daytime help.  Gram finally went to a home which was so much better for both of them.  Though it is wonderful to help a loved one in this situation, it can be devastating.  I highly recommend going to a support group, which mom would never do.  The support can be wonderful.

My friend took care of her dad for months while he had cancer. It was really hard for her. She had to quit college and move in with him and then she got laid off. Hospice helped a lot but she was really worn out. We all (her friends) tried to help as much as we could. I told my kids after he died that I want them to put me in a nursing home if I ever get bad. My friend told her kids the same thing. I don`t want to put them through that.