Do you have a client, that one "client" that is unpleasable, the one that okays a feature or design but is just never completely happy with it? These clients are not malicious people or evil, they just do not know what they want. Some times these clients can be herded along and taught but others resist such efforts. Their resistance may not be purposeful, it just may be an inability at the time.
A "client" like this ends up using all the time and resources available and will continue to do so until somehow the project is complete or until you realize it is time to say goodbye. This is a very hard decision to make but, once it is made and executed it can be very freeing because the drudgery of having to deal with that "project" or "client" is removed.
However, this is not just a "client" problem, having to say goodbye, also reveals an area for you or your company to grow. It indicates an areas that need improvement, such as screening potential clients and projects or in teaching clients the why and how behind their project. Take the need to say goodbye to a client as a call for improvement and evaluation of yourself and your company. Use this "bad" time as a growth point just as much as you use the "good" times. Use this to focus and evaluate the mission and scope of your company.
Having to say goodbye is painful yet at times neccessary, and is an opportunity for growth.