Most journal-type fanfictions do have the tendency to get explicit, but think about it this way; would you write almost every detail of your sex experiences in your journal? I find it's better when, in a journal fanfic, that the writer (character, not the actual author) writes about how it happened/started (did he/she or his/her lover asked to meet at a certain place, did it start with a passionate kiss and one of them asking to move it to the bedroom, etc), how he/she felt as/when it happened, and the aftermath (or [i]afterglow[/i] as some people call it). Once again, it's your call because it's your story.

That's all good insight! I'm a dude who's never even read fan-fic before. Seems like it would be fun to write, but I have no experience, so the advice is good.