Ask HN: How do you tell friends that you're choosing your startup over them?

As anyone who has worked on a startup knows, you pretty much have to sacrifice personal relationships in order to give the business the attention it needs to succeed. Unfortunately, I don't quite know how to tell me friends that I need to focus on work and I won't have as much time for them anymore. If you have any suggestions for how to do this without hurting anyone's feelings, please let me know.