Wa `alaykum as-salamu wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear sister, thank you very much for your question and interest to know more about Islamic teachings.
Though marriage is highly recommended in Islam, it is obliged only in some cases. Also, if one lacks sexual desire/drive, he is not sinful as Allah does not hold people accountable for things out of their control.
Responding to your question, Dr. Hatem Al-Hajj, Dean of Shari`ah Academy of America and a medical doctor, stated,
Allah Almighty said, “And one of His signs is that He created mates for you from yourselves that you may find rest in them, and He put between you love and compassion; most surely there are signs in this for a people who reflect.” (Ar-Rum 30: 21)
Also, it was narrated that the Prophet (peace and blessings be upon him) said, “O young people, let those of you who afford marriage get married as it will help them lower their gaze and protect their chastity. And for those who don’t afford it, they may fast for it will curb the sexual desire.” (Al-Bukhari and Muslim)
While marriage is generally recommended in Islam, it is only mandatory when one fears from succumbing to temptations and having illicit sexual relations.
Lacking sexual desire/drive is not a sin in itself, since Allah does not hold people accountable for their genuine physiological or psychological inclinations.
Moreover, one who lacks such drive may not marry without letting the other partner know of his/her condition. If the other partner agreed, then marriage would be permissible and even recommended if no harm will accrue to either partner. That is because marriage has many psychological, emotional and social benefits aside from the biological and physiological ones.
Avoiding conjugal relations on the basis of intellectual convictions that debase them would not be permissible, and would be clearly an act of defiance to the will and law of Allah and the way of His prophets and messengers and the righteous people since the creation of Adam and Eve.
Allah Almighty knows best.