How do you set boundaries with people who are trying to be nice?

Ok, so, I'm the type of person who has absolutely no problem putting someone who is outwardly rude to me in their place or standing up for the things I believe in. I sometimes get called a bitch for this, but ironically, this 'ballsy' side of me goes right out the window when it comes to people who aren't really *trying* to be mean but manage to drain me–intentionally or not.

I regularly find that clingy people latch on to me and can become a little over the top with their attachment and I don't know what I'm doing to give them the impression I'm interested.

I recently had a problem where one of my ex university professors who I began occasionally chatting with, started messaging me EVERY NIGHT for hours on end and asking what time I'd be available the next day as though it was an expected daily event. The guy was married and even if I liked him and enjoyed our conversations, I had other things to do and his undying eagerness began to feel super weird. I had to just ignore him until he eventually backed off, but it was really awkward.

I now have a girl who i vaguely know breaking my balls in a similar way. I know she has suffered with depression in the past and could use a friend, and I feel bad saying this but *I* don't want to be that friend.

This girl seems to have furiously latched on to me in a similar way to ex-prof and it's getting a little single white female-ish. She messages me excessively and I get the impression she's trying to mimic my way to talk. I'll write something on my FB wall and the next day she has tagged me in numerous memes and articles relating to what I posted. It's to the point where I don't think that it's possible she just co-incidentally stumbles upon these things, but that she's actively looking for them :s. I've had to block her on messenger. I  don't even respond to her and I've even tried subtly pushing her away by saying I'm busy, but instead of getting the hint, she's now just messaging me on my phone. I don't want to hurt her feelings, but I feel like there is no escape!

I realise this sounds incredibly narcissistic of me in itself: Look how, like...wonderful I am; people become obsessed with me! But I don't think it's because I'm this wonderful person, but that I'm obviously, unknowingly somehow giving off some kind of signal that attracts these sorts and I don't know how to turn it off!

Has anyone experienced something similar? How do you nicely but firmly tell someone 'nice' who can't take a hint to back off?

It's a hard step to tell people "no" but it's also one we need to learn. One way might be to say something along the lines of "I appreciate how nice you've been to me, but I really have too much going on. Your texts are a bit overwhelming for me now and I have some healing to do."

If they're truly "nice" they'll understand and pull back a bit to give you some breathing room. If not, then you can make a much more clean cut of it and tell them to please stop texting or calling. That's hard for many of us, but it's far easier than dealing with a future stalker.

Compliment for their kindness, give statement of need, don't explain yourself. A healthy situation will work out under those steps...unhealthy will be a big ol' warning bell. Hope it helps a little bit.

I have had a similar experience with this.
I found a friend who I thought was my BFF. We had SO much, almost everything in common. Except she was borderline. She mimicked me and would NOT leave me alone when I was spending time with my family or even sleeping. She didn't start off like that. She was DRAINING me.
So I asked for some time apart. She flew into a rage and contacted my exNarc husband and told him EVERYTHING I had confided in her, plus she made things up.
I ultimately had to block her from my life.
I have no clue how to handle people like this other than to not make friends. Lol, half way kidding and halfway serious.
Best wishes.

learning better boundaries http://buildbetterboundaries.com/

Thanks heaps, guys. I appreciate your responses. And of course a ginormous thanks to Richard.