It's permanent currently. I think what I'll do is add a way for the player to confess to a girl. If the player has already rejected a girl once, then it'll be up to them to move it forward if they change their mind.
Follow up question: Can/will characters that you put into the "Friend Zone" still move into a houshold with the player?edit: not sure but i guess it is possible to let someone move in who is friend zoned.