Have I committed a sin and wronged my religion merely by thinking of someone I love, and is love forbidden?

There is no blame for a mere inclination or attachment of the heart, as long as it does not lead to something forbidden or prevent an obligation. However, indulging in it can lead to infatuation that corrupts hearts. Marriage is the ideal solution for this attachment, for the Messenger of Allah, peace and blessings be upon him, said: "We have not seen for two who love one another anything like marriage." It is permissible for a woman to offer herself to a righteous man according to regulations and manners. If marriage is not possible, then you must turn away from this attachment and occupy your time with what benefits you in religious and worldly matters.