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” (I, ii, 126-131). Basically that everything he has said to her has been a big show to entice her into doing sexual things with him. He then goes on to suggest that she not see or talk to Hamlet anymore (I, ii, 132-134). Ophelia is so blinded by her love for her father that she fails to see how her actions are hurting Hamlet.
Apparently, a man in love and a man who has just talked to a ghost look and act the same way. When Hamlet goes to be comforted by Ophelia, the love of his life, her immediate conclusion is that he is maddened with love for her. The way Ophelia explains the way Hamlet was acting would make any woman believe that he was mad with love: “He took me by the wrist and held me hard. Then goes he to the length of all his arm, and, with his other hand thus o'er his brow, he falls to such perusal of my face as he would draw it. Long stayed he so.” (II, i, 87-91). Of course, she had no clue that Hamlet had just found out from his dead father that he was murdered by his uncle. Hamlet was probably just trying to figure out what was real and wasn’t real, so he went to the one person he knew would never betray him.
Though it is not directly said in the text, Ophelia’s father tells her to give everything Hamlet ever gave her back to him. This was to ensure that Hamlet didn’t pursue her any further. Ophelia was basically telling him that she didn’t want to see him anymore. This exchange happens right around the time Hamlet speaks