Where do I start???!!!
1. Some people do write everything in their diaries. I have a friend who writes down everything she eats and drinks, how many fags she smokes and how much she weighs every day (or is that Bridget Jones)
2. Whatever this girl is 'up to' he really needs to use a condom to protect himself as well as his partners, as he has already found out!! (STI)
3. Asking people about their sexual health really ought to be a face-to-face conversation not by text, they are too easily misunderstood, on both sides.
4. He should not be embarking on sexual relationships with people who he does not trust, as he seems to have done in both the cases you mention.
5. Is this you or a friend you are asking about?