comfort as she was of his love, "so loving to my mother / That he might not beteem the winds of heaven / Visit her face too roughly" (I.ii.140-2). His entire experience of the natural environment of home has been disrupted, and by actions that are plainly proscribed by the religious prohibition against marrying one's brother's wife. That explains his talk of home as an unweeded garden and of the marriage as incestuous sheets. Whatever hero-worship Hamlet had for his father, he retains after his father's death. But to the degree he has hero-worshipped his mother, he has been drastically disappointed.
The disappointment is especially keen because, as it appears, Hamlet has never particularly admired his good uncle, who as far as Hamlet is concerned is "a little more than kin and a little less than kind" (I.ii.65). He refers to Claudius as "My father's brother, but no more like my father / Than I to Hercules" (I.ii.152-3). Simply put, he can't figure out what Gertrude sees in Claudius. That bewilderment, combined with his memories of the love between Gertrude and Hamlet and his discomfort with Claudius's apparent determination to involve himself with his nephew, not merely as nephew but as son, unsettles Hamlet and makes him adopt the "inky cloak."
The fact that Hamlet has been sulking is indicated by the concern both Gertrude and Claudius have that he has not remotely gotten over his grief. We find out that Hamlet is almost obsessed with the memory of his father, whose image he retains in his mind's eye (I.ii.185) and upon whose like he expects never to look again. Hamlet's admiration for his father, grief at his loss, and confusion over the marriage seem to have had a cumulative effect so great that he has reached despair and has had thoughts of suicide. "O God! God! / How weary, stale, flat and unprofitable, / Seem to me all the uses of this world!" (I.ii.132-4). The idea that life itself has purpose has no attraction for him. It...