What is the ruling on one who swore an oath by divorce that his daughter would not see her colleague at university, then the young man proposed to marry her, and how can the marriage be completed without the divorce taking place?

If a wife swore an oath not to see a non-mahram man, and then he proposed to her and she married him, no divorce or breaking of the oath occurs if her intention behind the oath was not to see him in a forbidden or illicit context, and marriage is not such a context. Oaths are interpreted according to the intention of the one who swore them. If a general oath has a specific reason and a particular intention, it is directed towards that intention.