To make a living as a freelance technical writer you must usually have several projects going in parallel. I have noticed that each client does not want to hear about your other clients, and the last thing that they want to hear is that you are busy with another client and can’t come right over to work on their project. Even though they know that you couldn’t possibly be making a living from their 10 hours per month, they like to pretend that they are the only one. This is very similar to dating several women simultaneously and making no serious attempt to hide this fact (Please note–before accusing me of sexism I am writing this from a male viewpoint). All the women know that you are seeing other women but they don’t want to hear about it.
Finally, this reminds me of an article I once read for parents with a small child about how to break the news to the child that mommy is pregnant with his rival. According to the article the worst thing that you can do is tell the child that because you love him so much you decided to bring another baby home. It would be like your wife coming home one day with a man in tow and saying that because she loves you so much she decided to bring another husband home.