Without theorising the answer to your question too much, I would mention here the three ego states that the theory of Transactional Analysis deals with. They are the 'Parent', 'Adult' and 'Child' ego states. Even Sigmund Freud, considered to be the father of modern psychology, has explained something similar when he spoke about Id, Ego and Superego. The 'child' within our mind seeks unlimited pleasure, satisfaction, enjoyment, approval, appreciation, care etc. mostly without considering the risks involved in the process of the fulfillment of such needs. The 'parent' within will keep cautioning on the risks, but in the cases of feelings like in romantic relationships, such cautions from within do not get accepted and considered by the 'child' which will internalise the relationship like an addiction. It is the 'adult' within us which can balance between the child's urge to cling despite the caution from the parent. The adult is the maturity within our mind. Psychological counselling and psychotherapy can strengthen the 'adult' within and make a person see reasons and become sensible. So, if you are unable to handle your situation (the urge to leave which probably is because of the cautions from the parent within), please consult a psychologist and find ways to strengthen your 'adult' and overcome your urge to cling on, which may even be leading you to a situation of self-harm.
Next Steps
Please consult a psychologist.