How would you describe Polonius and Ophelia’s relationship?

Overall, one could say that Polonius and Ophelia's relationship is a fairly typical example of what we might expect to see between a father and daughter at that particular time. Polonius is very protective towards Ophelia, seemingly always looking out for her best interests. He knows that she's young and more than a little naive and, therefore, largely innocent in the ways of the world. As with just about everyone in the play, Ophelia is often subjected to Polonius's advice, whether she asks for it or not.
Although we may find Polonius a tad over-protective at times, we can still understand his suspicions towards Hamlet's courtship of his daughter. It would seem that Hamlet, as a prince of the realm, would be quite a catch for Ophelia. But Polonius is implacably opposed to any match between them. For one thing, he wrongly thinks that Hamlet has been driven mad by his unrequited love for Ophelia. This shows Polonius' seemingly endless capacity for getting the wrong end of the stick. Not only is Hamlet not really mad (as Polonius himself half suspects), but Ophelia is genuinely in love with him. She is deeply impressed by Hamlet's professions of love, so it's all the more important that Polonius exercises his fatherly authority and forbids her from having anything to do with Hamlet.
Ophelia's rather confused by all this. But she remains a loving, dutiful daughter and so complies with her father's orders. It would seem that Polonius has carried out his duty as a caring father should.
However, it's difficult for us to shake the nagging suspicion that Ophelia is being used as a pawn in a game of high politics. Perhaps Polonius discourages his daughter's relationship with Hamlet because he doesn't hold out much hope for the prince being around much longer. Claudius is the king, after all, and it's to him that Polonius owes his primary loyalty. If that truly is the case, then this puts a different complexion on things. We have no reason to doubt that Polonius truly loves Ophelia, but at the same time, Polonius is very much a man of his time and class. As such, he needs to consider the bigger picture, the world of statecraft, and where he and his daughter fit into that world.