When do you become "single"?

It's been a long time since I posted, partially because I lost the log-on information (again.) The truth is, the more time that passes, the more single I feel. My marriage, which began its precipitous downward slide exactly ten years ago, now seems like a distant memory. I no longer miss Bob. And I am no longer frantically searching for a male companion. If I meet a man, he will catch me unawares, doing something I like, and most likely laughing.

Time is slipping by quickly and I rarely feel alone. The best post-divorce actions I took were to fill my house with tenants (especially in this tough economy) and acquire a dog. I have a challenging job, and I keep stretching myself, acquiring new skills and trying new things. My only regret is that I did not take care of myself physically, and my couch potato-ness has affected my health. So for the foreseeable future I will be spending my free time at the gym, and walking the dog, and eating wholesome foods.

Several of us had this discussion recently: When do you become single again? Is it a state of mind? In filling out an application form, when do you check the singles box instead of "divorced"? What are your thoughts? Here's an online discussion thread on the topic.