Going back to Lizzie, there has always been something more than friendship between them. With stronger feelings on her side admittedly.
At one stage he tells her she stopped his heart from breaking (I can't remember if this was after Grace left him to go to America or after she died).
Also when the Shelby Company ladies walk out of their work to join the women's suffrage demonstration (season 3?) Lizzie complains that Tommy has been bending her over the desk regularly.
Even in the first episode of season 4 I felt that Lizzie was jealous when she heard Tommy asking for prostitutes to be brought to him.
Lizzie also owes Tommy a great deal as he has elevated her from a prostitute to a wealthy business woman.
Anyway, as you we're!