Does she make an effort to introduce you to her friends? Attend outings or have a social life with and without you? Encourage you to make other plans without her involvement (a night out with the guys)? These are all healthy aspects of a balanced relationship. If she always wants to stay inside alone with you, gets irritated when you socialise with others or make plans, or expects you to spend every waking moment with her, this is a sign of extreme possessiveness. Remember, nobody has a right to isolate you from living your own life.