Most people would call them unreliable.

As to why they are unreliable can have many different reasons. If it is you or someone else don't be quick to judge. Lots of different problems can cause this.

For example my depression causes me to be unreliable. For a long time I would tell people what they wanted to hear or make commitments because I really wanted to fulfill them. All the best intentions but could often not follow through. I had to learn not to commit to things I may not be able to do. I can't help being deeply depressed at times but I can be realistic about what i can do. If I take on a big job that is going to happen a month from now and I am doing really good right now, I am still taking a risk that I won't be doing good in a month. Usually it always works out. I think only twice I had to cancel jobs and the people were understanding. My daughter and family it is different. I have let them down many times in the past. Even now if I don't make any promises or commitments if I can't make it to Thanksgiving they are disappointed.