Is a girl's repeated emotional attachment to different people - even if there is no forbidden relationship - considered polytheism (shirk) with Allah or a psychological illness? And what is the interpretation of this condition that prevents suitors from proposing to her?

Feeling love before marriage is not polytheism (shirk) if it is a natural love and not a doctrinal one. One must be wary of obsessive thoughts that could lead to psychological illness. It is permissible for a woman to propose marriage to a man of good character and religious commitment, whether directly or through an intermediary.