From my point of view, Polonius is concerned about Ophelia and appears to be a very caring father. When Ophelia reveals her relationship with Hamlet, he does not approve it. He strongly believes that she is fairly being used by Hamlet and their relationship is nothing but fun in terms of Hamlet's feelings to Ophelia. He says “ Affection! pooh! you speak like a green girl”;Do not believe his vows, for they are brokers”. Polonius considers her to be very naive and immature and he clearly says it to her, thus forbidding any private communication with him. This obviously shows Polonius as protective and responsible for his daughter. But on the other hand, he is too controlling over Ophelia and Laertes, too. He does not take into account on what outcomes it may lead to in terms of Ophelia's tender feelings. Moreover, he literally governs her by setting her up to check Hamlet on his both madness and love in Act 3, Scene 1. Still, we cannot say that this is a bad thing as such relationship between father and daughter was common at that time.
How does Hamlet speak to Ophelia?/What do you think Hamlet feels for Ophelia?
To my way of thinking, the relationship between Hamlet and Ophelia can be considered as real before Hamlet's father death. As far as I can see it in the play, they used to have private meetings, which Ophelia may have taken seriously due to her young and naive nature. Though for Hamlet, it is nothing but fun or fairly amusement. Such people like Hamlet would never consider love as the purpose of their lives. So when the king of Denmark dies, Hamlet's behavior to Ophelia considerably changes. He has no longer any time for fun, all his thoughts are full of revenge, which is evidently more important to Hamlet, than love. So he leaves Ophelia and does not hesitate to say it face-to-face, even in a sarcastic way -You should not have believed me; for virtue cannot so inoculate our old stock but we shall relish of it: I loved you not. / Get thee to a nunnery: why wouldst thou be a breeder of sinners? /
The way Hamlet speaks to Ophelia, for instance, in his letter and in private, while Claudius and Polonius are hiding behind is completely different. Last but not least, in that scene he speaks in prose to her, which, I believe reveals his real attitude to Ophelia.