One of the funniest (read:ironic) about writing is that you being a writer is what often attracts you, as a writer, to people, but, once you write about them (or to them) in a public space (read:blog or a book-remember them?), then you run the risk of really upsetting them. No easy answers here. You have to tread the line carefully between making people feel uncomfortable and satisfying that undeniable urge to immortalize people in print. Of course, you can always just write in a notebook, but that loses the sense of importance and celebration that comes with the wonders of web 2.0 publishing. Too personal writing aside, because it doesn’t work for this example, you could always use pseudonyms. Risky, of course, if you’re trying to tell that special person that you love them. I mean, if you’re trying to tell, say, Sheila that you love her, it’s hard when you’re writing a poem to Brenda.
I’m not sure there is an answer here. Just be careful what you post and hope that it doesn’t freak out the person you’re writing to. I’m hoping to learn that eventually.