Upon the death of his father Hamlet's uncle imminently, and eagerly for that matter, marries his mother (Gertrude) This act of incest largely colors Hamlet's relationships in the play. Hamlet becomes practically obsessed with the relationship between Gertrude and Claudius. I think, for Gertrude, marrying Claudius was an easy out. It wasn't a societal norm, even in this time period incest wasn't considered normal. It wasn't her civic duty either; it was an action done so she could remain in her own comfort zone.
Not only this, but Hamlet becomes very cynical towards women in general. With Ophelia, there is always that constant struggle for control. Ophelia becomes both intrigued, and utterly confused by his erratic mind games. Hamlet becomes a misogynist; he has a very blatant hatred of women. We see his emerging opinion of female sexuality, the very sin, and how it leads to moral corruption. For instance when Hamlet remarks to Ophelia "get thee to a nunnery." He is suggesting to Ophelia that she "save her soul" before it is too late.
Would I have taken on the same roles if I were Gertrude or Hamlet? One can never know, but I can definitely understand their actions.