Yeah - I gathered that she always loved him - even when he was married, and now she's taking advantage of the situation. Note the line when Sweeney finds out she lied to him about Lucy "I'll be twice the wife she was"
He has no romantic feelings towards her at all.
Madame Morrible: "So you take the chicken, now it must be a white chicken. The corpse can be any color. And that is the spell for lost luggage!" - The Yellow Brick Road Not Taken