As long as you have had the talks with her about birth control, not having kids too soon, and prioritizing her education for the benefit of her whole life, the only thing I would do is require my D to have separate housing until she graduates. Not because of disapproval, but because of possible consequences if they break up. They can be together as they choose, but I think that when education is the priority, having separate space can prevent potential problems.
As far as spending time with him instead of others, eh. There is more than one way to have a good experience, and others may couple up over the years.