Unreliable

There are lots of people in my life that I consider particularly unreliable. As I sit here typing this at almost 2 am, I am reminded of why I consider there people unreliable.
I find that even when I try my hardest to be reliable for these unreliable people, that I get my good deeds and nice gestures thrown back in my face. I understand that in some situations things happen and not everyone can be available, but I think that it is perfectly reasonable to expect someone to be there for you when you arrange things months in advanced. I am sure that this person will have excuses and apologize profusely, just in time to ask for the next favor from me and I am quite finished being available.