This was originally supposed to be a comment, but the thread was deleted, so I figured I'd just start one:

When someone close to me gets something (could be anything from a clothing item I normally wouldn't choose to a new hobby), I find myself wanting it too. I don't mean in a jealous way, (not that I don't have that too), it's more "do I really want this, or do I just want it because x has it/is doing it?"

I just realized: so? Why is this behaviour pathological? People see 10 second video clips of someone fictional enjoying the hell out of something, and everyone knows the *I never even knew that existed, but I need it!* feeling advertisements give you. (Skymall, anyone?)

In that case, wouldn't seeing someone real - someone you like or love and share other interests with - enjoying the hell out of something have a stronger influence? If I'm seeing their enthusiasm for it, why shouldn't I get caught up in it? I do want that thing. Why is it any less valid? 

Nobody questions "do you *really* want that Activia? Are you *sure* you don't just *think* you want it because you saw that photo of a woman enjoying yogurt way too much in that magazine yesterday? Is that the *real you?*, or are you having trouble separating yourself with that woman who has orgasms over dairy products in stock photos because of your unstable sense of identity"?

I think that's a hell of a lot more bizarre. Why is one "normal" and one "Borderline"? If you want it, you want it. Full stop. A way of thinking isn't a problem unless it's destructive, and for me, as long as jealousy isn't involved, this is no less destructive than advertising is (financially and time-wise, like it is for people without BPD?)