Hormonal changes associated with your menstrual cycle, aging, menopause, childbirth and breast-feeding may be the factor.
Vaginal dryness during intercourse may also mean that you aren't sufficiently aroused. Make time to be intimate with your partner and allow your body to become adequately aroused and lubricated. It may help to talk with your partner about what feels good. Having intercourse regularly also may help promote better vaginal lubrication.
Fatty fish like salmon and sardines and flaxseeds are a good source of omega-3 fatty acids. It is very important for you to have these foods as they keep the cells healthy. Take flax oil and fish several times a day. You can also have 1 or 2 tbsp of flaxseeds which have been freshly ground in place of flax oil regularly to treat vaginal dryness.
Avoid using scented or perfumed products, including toilet paper and detergents.