Why was Lumen so unpopular?

I loved her chemistry with Dexter and I thought he really cared for her .. it seemed that he really loved her .. he was sad when she left I guess if she had stayed they would have been together until the end .. what are your opinions?

I loved her chemistry with Dexter and I thought he really cared for her .. it seemed that he really loved her .. he was sad when she left I guess if she had stayed they would have been together until the end .. what are your opinions?