Hmmm... that last sentence, pelourinho.  I never stopped to think about it that way... and it does make a lot of sense. 

On that side of the coin, guys... do you find that your male protagonists are a lot like yourselves, or someone you could root for getting the girl at the story's end?

Some girls deserve a good girl too...

 

~Mimi

I think in any lengthy story, the author draws on him/herself and people they know for inspiration.  A protagonist might not be based on any specific person, but maybe an archetypal amalgam of whom we know.  Assuming the author is male, the protagonist might be autobiographical in nature, or at least might share some common traits with the author.  But since it is fiction, as an author you want to use the opportunity to exaggerate or distort some traits of the people you know.  Maybe you idealize certain character types, like in one story the male lead might be the way the author sees himself.  In another, it might be the way he would like to see himself, or maybe the way that others perceive him. 

Part of the fun of fmg literature is the opportunity to start with characters with familiar personalities and to depict how they would react in a fantastic situation.

Unless, of course, what you're writing really isn't intended as anything more than verbal self-stimulation    Nothing wrong with that- just keep it in mind.  If you intend to have your story have more depth than that, though, than the SO needs to bring something to the relationship that the protagonist can't readily provide for herself.  That 'something' could be any number of things- a different emotional perspective, understanding, sensitivity, security, vulnerability- whatever it is that the protagonist needs reinforced or provided from an external source.