It means you are in menopause.
When you are in menopause your hormone levels and genitals return to the state it was as a pre-pubertal girl. Everything 'deflates' and becomes thinner and less flexible.
Discuss this with your doctor.some hormone replacement therapy can counteract this.
Regular arousal and orgasms ( intercourse or masturbation) will also keep these tissue more healthy for a longer time.
You may also be drier, with less vaginal discharge and cervical mucus. So remember to use personal lubricant to keep things slip sliding.
Best of luck!