Due to the rapidity of with which Bel-Imperia falls in love again, it is easy to doubt the degree of her love for Horatio and even for Andrea. Not long after Andrea’s death, Bel-Imperia was already interested in Horatio. Her servant Pedringano tells Lorenzo about her feelings towards Horatio “She loves Horatio.” (2.1.79) Once again, Bel-Imperia falls in love with someone of whom her father does not approve. It is questionable whether she loves these men, or loves the freedom these men can provide her since they are not in the same social class as her. The play does not clearly depict Bel-Imperia’s feelings clearly. It seems as though Bel-Imperia merely decides with whom she will fall in love with, but her psychological details are not provided. Bel-Imperia fought for Horatio’s revenge and ultimately ended her own life. Bel-Imperia even resented Hieronimo for believing he was not seeking revenge, even if revenge meant going against her own brother Lorenzo. She wanted to take revenge onto her own hands “And give it over and devise no more, / Myself should send their hateful souls to hell / That wrought his downfall with extremest death.” (4.1.27-29). She helped Hieronimo with his plays to seek revenge against Lorenzo and Balthazar. Bel-Imperia was loyal to Horatio, even after his death.
Similar to this is Beatrice- Joanna. It is questionable if she truly loved Alsemero or just wanted things to go her way. Although Bel-Imperia killed for revenge, Beatrice-Joanna killed to marry to Alsemero. It can also be questionable why Beatrice-Joanna did not love Alonzo. The play never goes in detail as to why she did not want to marry Alonzo, but instead quickly falls in love with Alsemero. Beatrice-Joanna does in fact later admit to Alsemero what she has done, and that she did it for him.
The wheel has come full circle; there’s a lot left unsaid in The Changeling about Beatrice-Joanna’s motives, but the play gives us a sense of psychological density that is missing in The Spanish Tragedy, as you indicate.