I think its completly healthy and normal, everyone at some point fantasy being married, dating, having children or relations with someone.Oh my... I've had so many, I don't think I could name them all. Some have certainly been sexual, sadly.
Some have been from shows, some from movies, some online, and one or two even from a book.
I've played out scenarios in my mind while out and about, doing my daily things. It's sad, and at the same time, it's so me, it seems natural. I think it has something to do with not being able to fulfill something in my life, so I have to make things up in my head. I sound crazy, but I'm really not.