I've got to leave for work but just had another random, disturbing thought that I thought I should throw out there...
For 5 years he has been asking you to move in with him. For 5 years this hasn't happened.
WHAT IF, at some point during those 5 years, he came to the conclusion that it just was never going to happen? WHAT IF he kept asking because that has been part of your "dating dynamic" and he didn't want to rock the boat? WHAT IF, he (consciously or unconsciously) has been structuring his life/other relationships on the assumption that the asked for move was not ever going to happen? WHAT IF, now that you have finally agreed to move in he is having second thoughts about what he has been asking for?
That would suck if it were the case
- but better to address it now than AFTER you have moved in.