What is the ruling on the transgressions committed by the questioner with his fiancée, then leaving her, then proposing marriage to her again and leaving her a second time, and the resulting feeling of guilt towards her?

A suitor is a stranger to his fiancée until the marriage contract is concluded. It is impermissible for him to be alone with her, touch her, or speak to her without need. Lenience in this matter leads to calamities. The statement "You are my wife before our Lord" does not result in a legally valid marriage. What is obligatory is sincere repentance by abandoning the sin, regretting it, and resolving not to return to it. Marriage to the girl is not a condition for the validity of repentance; rather, part of sincere repentance is avoiding the causes of the sin.