My Boyfriend is Bi but denies it. I am fine with the orientation but not the lying about it. Any suggestions?

I have asked him about it and even told him that, if he is, I don't care. I just want him to be honest. I even went so far as to show him one of the profiles I found online and he claimed to have no knowledge of it and stated that someone must have created it as a joke. I know he created it because it is a log in name that he has used elsewhere with a pword he had previously shared with me for other things. I also know he has been browsing the gay personals and watching gay os on-line. Again, I don't care, but how do I help him to understand that?