Did Hamlet really Love Ophelia?

In the play, Hamlet.. One of the biggest questions was if Hamlet really loved Ophelia. Hamlet says to her, " I did love you once." four lines later he says, " I loved you not." consider these lines as well as Ophelias conversation with her father, brother, Hamlets love lettters, and his treatment for her throughout act 3 and 4. Does he love her, and more importantly, how does the fact whether her did or not effect the play. Please help, im not sure.