True LOVE conquers all, right?

Even Death... so why do so many remarry and love again? I mean I could never imagine this if I lost my wife to death. I just feel the love would still be there and continue forever... so how do so many that experience the death of their spouse that they love so much end up loving again? Even remarrying? Don't you feel you might meet again in Heaven (for those that believe in Heaven) or somewhere in the afterlife? I hope and pray I never experience this but if it ever happened I just can't fathom loving again without feeling guilty or having a feeling of betrayal.