What did I do to deserve this?

What did I do to deserve this?  I go through life trying to help people on a daily basis.  I'm always nice, polite, and respectful to the people I meet and especially the guys I date. . .why am I the one that always gets used, hurt, and treated poorly?  I don't do anything to them. . .how is that fair?  Why do people feel like they can walk all over me and anything I have to offer is theirs for the taking?  Its not just a one time occasion either. . .its every freaking time. . .and its not fair.  I don't deserve that.  I deserve better than that.  I at least deserve a little respect. . .some kindness. . .decency.  Don't I?  Or is my kindness towards others all for nothing?  Haven't I dealt with enough?  Can't it just stop for a little while?  Please?