What is Ophelia's interaction with Polonius in Act 1, Scene 3 of Hamlet?

Polonius advises Ophelia against a relationship with Hamlet.

Laertes, Ophelia’s brother, counsels her to avoid Hamlet’s advances. He tells her that royalty is fickle and she will just get hurt.  He is her brother, and he is looking out for her.  Then her father enters, and asks what Laertes advised.

Ophelia tells him they were talking about Hamlet, and Polonius adds his caution to Laertes’s.  He tells Ophelia that he is aware that she has been thinking about Hamlet, and that she should be careful.  Like Laertes, he does not believe that Hamlet’s intentions are pure.

OPHELIA

He hath, my lord, of late made many tenders
Of his affection to me.

LORD POLONIUS

Affection! pooh! you speak like a green girl,
Unsifted in such perilous circumstance.
Do you believe his tenders, as you call them? (Act 1, Scene 3)

Poor Ophelia is getting it from all sides!  She is a sensitive girl, and she does not want to question Hamlet’s integrity.  However, her brother and father see her as a vulnerable damsel and feel the need to intervene before Hamlet takes her honor. Ophelia assures him that Hamlet’s intentions are good, but he tells her it is all an act.

For Lord Hamlet,
Believe so much in him, that he is young
And with a larger tether may he walk
Than may be given you: in few, Ophelia,
Do not believe his vows; for they are brokers,
Not of that dye which their investments show,
But mere implorators of unholy suits,
Breathing like sanctified and pious bawds,
The better to beguile. (Act 1, Scene 3)

In a way, the two men are right.  Hamlet is not to be trusted.  He may have feelings for Ophelia, but he manipulates her and uses her very badly.  He must see how fragile she is, but he continues to mess with her head.  He has bigger problems than her.  He wants to make everyone believe he is crazy because he needs to avenge his father, and she is just the tool to do it.