Sexual desire is a biological urge. Hunger is also a biological urge. You should feel no more guilty about experiencing sexual desire than you should about experiencing hunger. Both are natural, biological urges. Once those urges or needs are satisfied, you move on. Sexual desire is a feeling that should produce no guilt or shame. You don’t eat every time you are hungry but you shouldn’t feel ashamed of feeling hungry.
At some point your life, you came to associate sexual desire with something that is shameful. It’s likely not something that you can remember and it may have been a benign event that led to the association. You stated that you do not have a history of sexual abuse but many people who have been sexually abused have no memory of the event, even multiple events.
A sex therapist could assist you with this issue. A sex therapist is an individual who specializes in the sexual aspects of relationships and helping individuals to develop a healthy sexual life. As you noted, this issue has prevented you from developing healthy relationships. The inability to participate in romantic relationships will disrupt your happiness. In that sense, this is a major issue that needs to be addressed. Sex therapists deal with these types of issues on a regular basis. Don’t ignore the issue or simply hope that it will go away. With treatment, this problem can be resolved. You may only need a few sessions to break this association. I hope that you will consider it. Please take care.