My boyfriend always wants sex, I do not

My boyfriend is always on me to have sex. It was great in the beginning. We both did not work at this time, now I work m-f and he works only full time 10 days a month. To add to this I have had 2 surgeries one in December '09 and one in June '10 the last one was due to being pregnant and losing the baby and a fallopian tube. There have been some issues with his grown daughter as well. I do not feel like having sex all the time, and he keeps saying to me things are going to change and a bunch of non-sense that is not kind. He is a "good guy" but I feel that he focuses on sex way to much. He has a lot more free time than I do now, and everything his daughter does is great (she is unmarried and has 2 kids and did not work until recently also she and I have issues due to some missing money) and the grandchildren are a whole other topic. He always changes when he is not working with a set schedule, not his other job he does at his leisure. Is this a lost cause??? Is it all me as he claims??
Plus he brings up my past quite a bit, i feel that this is wrong to do.
Is this possibly a MLC ???

Noel's response

It is not all you, although it might be partly you. I suggest marriage counseling, and if he won't go, you might want to consider whether you want to carry on with this relationship.

It doesn't sound like a midlife transition as much as it does a man enmeshed with his daughter. He also sounds pretty inconsiderate of your needs.