Let me clarify my point.
Firstly, I am a blogger, I have blogged all my business. So, this is totally applicable to me.
Secondly, I definitely appreciate the reasons you put down for blogging as that is how I feel too...
Buuuuut, I have in the past felt pressure by a (former) partner to change what I wrote in my personal blog because she was unhappy with something I wrote. This made me very unhappy and restricted and for that reason I would have preferred if she had never known about the blog (note, this was not a problem with other partner who is more wont to use things I write as a step off for discussion).
I wouldn't ask other partner not to read my blog, he already knows it exists and I don't think it is fair to say 'hey dude, I have this blog, in it I write about our relationship, how I am feeling and what currently pisses me off about you, other people read it and sometimes offer support or suggestions but don't read it'
That to me is a bit (lot) cruel....but I accept some people feel that is a totally valid thing to say to a partner but I don't. If I want to have a private space than I will have a private space without dangling my 'Warhammer' blog in front of them like Pandora's box.
I suppose some people might think it is dishonest to have a blog/space that your partner/s do not know about, but I don't because I am an individual with a right to a certain level of privacy but I need not be a dick about it.