What is the ruling on a male student standing with his female classmate to exchange notes and explanations, and a young man standing with his female acquaintance under the pretext of engagement, whether it materializes or not, and engaged couples standing together?

It is permissible for a male student to stand with a female student to give her notes or clarify academic matters, provided certain conditions are met: that both are committed [to religious principles] and known for their chastity, that the female student is modestly dressed, that they lower their gaze, that there is no khalwa (definition) (private seclusion) between them, that there is no fear of fitna (temptation), that the conversation is limited to academic matters, and that the female student avoids softening her voice. However, standing together with the intention of merely finding an "excuse" is not sanctioned by Islamic law. If the relationship implies a legitimate marriage contract, then there is no harm in them standing together. But if it is merely an engagement, then they are still non-mahram (definition) to each other, and the aforementioned guidelines must be observed.