You know that feeling of doing something nice for someone or being really helpful? Then, not getting thanked for it? Ouch.
If I had a dollar for every time I heard someone complain about not being thanked for a gift or service I would be very rich, indeed. Don't get me wrong, it is always wonderful to be acknowledge and appreciated for something we've done to help someone else out. However, there will be just as many times that it is overlooked or forgotten.
Trust me, I have been on both sides of this coin. And if we are all honest with ourselves I'm sure we can think back to times we still hold a grudge towards someone we think should have thanked us. Or, they did end up thanking us but it was such a pitiful attempt that it comes across as insulting.