Intimacy is at the heart of a strong relationship. Intimacy is about being able to be free, to be your authentic self with them. It's a deep emotional bond that is normally reserved for just one person. Ideally, sex in a loving relationship should come from a place of love and connection. The two are interconnected intimacy builds sex and sex builds intimacy. When one is struggling, the other is also.
If you and your partner are having difficulties couple therapy can really assist.