For a growing number of women, declining hormones, job stress, relationship issues, and other problems are taking their toll in the sex life. Loss of sexual desire, known in medical terms as hypoactive sexual desire disorder (HSDD), is the most common form of sexual dysfunction among women of all ages. There are other reasons also such as your relationship with your spouse,  emotional connect with him etc.  Sociocultural influences such as work stress, negativity influencing sexual drive, medical problems that is low testosterone,  thyroid disorder, depression etc. Please consult your doctor for a complete diagnosis and assessment. There are medication to cure whether it is physical or mental related issues.