This is by Wikipedia, a common characteristic in people with BPD.

I don't think I have BPD, but my father, who is adult child of an alcoholic, acts this way constantly, and it impacted my life so much that I attract into my life people who also have this excessive need to be nurtured, and they at first carefully detect this helpfulness that my father programmed in me, and than slowly suck me into their lives and keep me around them; they give only as little to keep me around and take so much, exploit, 'till I emotionally bankrupt.

Even this morning, one of my friends (with these tendencies) texted me with a question that he cannot find something on the internet, and I am overwhelmed with this hundred and first request that I am sure he can manage by his own, but what he really wants is a sense of nurturnce, a sense of virtual parent for what I don't have capacity anymore.
And my day went wrong immediately with this SMS.

Because of these people, I think that the day of me wishing to have kids will never come, cause I will hate everybody who will have even a realistic need to be helped or nurtured.

Now, don't get me wrong. I understand this my friend who lost his mother when he was a boy, but I cannot fill his emotional void and what I feel by giving him help is ENABLING and wasting my time into one big black hole.

My ex girlfriend once beautifully said his characteristic:
"He can very well detect people which he can exploit."

But at the end, our friendship is based on both sided pathological mechanism.
It takes two for relationship to function.

My question would be, is there any healthy adult way out of this dynamic?
As I said, my emotions bankrupted and I don't have words to send him.
All I can do is to ignore him and feel that he is hating me cause of that.

Thanks a lot and sorry for a long story.