Ask that particular woman exactly what she means and if you still don't understand after she's attempted to explain don't be surprised (complicated creatures) lol.
It means she is not into you that much, any more. Pure and simple.
It means you're being too clingy and needs time and privacy for herself.
It probably means you're being overly needy with her and she needs you to back off a little bit.
She needs some time to think over things by herself.