I Dont Get It

I have always had a hard time understanding kindness. I've often felt confused or suspicious if someone was being nice to me. Genuine kindness. The kind where someone buys a homeless person something to eat instead of ignoring them. There have been times in the past when I gave a friend a place to stay or gave my last few dollars to someone else who I felt needed it more. If I am on the receiving end I cannot understand it. Why am I being treated nicely? Why are you helping me? I can't help but to think they want something from me or are trying to get close to me to hurt me by trying to gain my trust.