Why do you have someone you're not really friends with on your friends list? It's kind of like willingly going back to junior high where you had everyone in your business regardless of what you thought of them.
On my FB page I constantly see updates where Friend A has posted to Non-Friend B. It doesn't involve me at all, and I don't even know person B, but they are friends with A. I've had to delete several comments I've made because I realize after the fact that my friend actually posted to someone else or they commented on someone else's post and it showed up on my page as well, confusing me into thinking they'd posted to me. It's really frustrating and annoying!!
I played around with the settings and as far as I can tell you're stuck with that unless you want to make it so that you *only* see what people post directly to you (or in their own statuses, of course) and your friends can *only* see what you post directly to them. That means we'd miss out on a lot of funny conversations that get going between several mutual friends.
I just installed Social Fixer (the updated version of Better Facebook) and used it to attempt to filter out some of that extra junk, so we'll see how that does.