What is permissible for a young man to talk about with the girl he loves, without falling into falsehood or secrecy?

If a man's heart becomes attached to a woman without his seeking it, there is no blame upon him. What is prescribed for him is to propose to her. If he is rejected, he should turn away from her. If marriage is not feasible, he must rid himself of this attachment. As for speaking between a man and a non-mahram (definition) woman without need, it is not permissible because it is a cause of fitna (temptation). However, if there is a valid need and fitna is secure, then there is no objection, provided the limits of Sharia (definition) are observed.