I generally just say something like, "Yeah, there are a few guys I'm seeing," or simply, "I date." Because that's what I do - date, see a few guys. For marital status on forms, I choose "Separated" if that is one of the options, because that's what I am. I don't often bother with long explanations unless it's someone I'm close to or friendly with and it's appropriate to the conversation.
The world opens up... when you do.
Oh, oh, can't you see? Love is the drug for me. ~Bryan Ferry
"Love is that condition in which another person's happiness is essential to your own." ~Robert Heinlein