It's not uncommon for men to want to be alone or lose interest in their partner right after sex. It has to do with the way the brain chemicals change.

Men have a dopamine response that sets them up for it, their job being done for the moment. It can also make them tired or sleepy.

Women on the other hand have a release of a brain chemical that makes them desire contact. So they want to cuddle. It's reassure to them, and helps them feel that they won't be left alone.

So the long and short of it?

If you like the woman at all, stay awake and cuddle with her, so that she'll feel safe and protected.

If you don't really care and want to keep her on the hook for later sex, head out and get away from her, which will force her to feel badly about herself and try to pursue you.

Your feelings are normal, but what you do with them are up to you.