My husband and I recently went through this very issue. I post on a different board (fan site for a show he has never watched). He comes from a very dysfunctional childhood but is a survivor and turned himself into a wonderful, gentle, loving man (talk about pick of the litter). That of course does not mean that he is unscathed by his childhood, who is? At almost 50 he finally got to a place where he needed to deal with the childhood stuff and became aware of how it has effected his life as a husband and father to our kids. One of the things that he was struggling with is the guilt and frustration of realizing that he has never really heard me as a person. Before he took on this challenge there was a period of time when I knew it was coming but could also see that he had to come to the decision on his own to seek help. So I would escape my frustration though the fan site and by being in contact with an email circle that I am part of. I have always used a nom d' plume on the internet (strick rule in my house since the day my kids started using the internet) and so didn't think anything of it. One day my husband went on to the fan site and surfed around a bit. He recognized me from my posts even though I used a psuedo to identify myself. For him it was about trying to deal with the fears that being in therapy brought to him about my wanting him in my life (long story and his story so I won't go into it)and trying to more fully understand who I am, to me it was a breach of trust. He talked to me about the fan site and told me that he had been on it looking around. Since trust is one of his issues he got right away why it was an issue for me. It would not have been a big deal if he had told me ahead of time that he wanted to check out the site but because it was my way to have some private time and a break from what swirls around me everyday it felt like he had gone behind my back. He no longer goes to the site and has actually spent quite a bit of time beating himself up over the entire incident.
My advice, be sure how you feel about having him on the site in the first place. If you are talking about things here that you don't talk to him about is this a substitute for things you should be discussing with him? Are you just venting on this site? Are you using it as a trial run at an issue before you talkt to your boy friend? Let your boyfriend know that this is a place that you talk about personal things so that you can gain some perspective on all aspects of your life. Tell him that you think this is a site that would be beneficial to him but that he needs to understand the kind of support that you get here and that you are not willing to give that up. Chances are he will be curious enough to log on. You may have some interesting conversations come out of it and you may have some conflicts come out of it. Either way, strong relationships have to be able to move through difficult issues or the relationship won't last anyway.