What is the moral conflict in "Rappaccini's Daughter"?

In his story, "Rappaccini's Daughter," Hawthorne raises a question proposed by others such as Victor Hugo with his character Claude Frollo and Mary Shelley with Victor Frankenstein: What are the ethical boundaries of science? 

When science infringes upon love, there are horrific repercussions as in Hawthorne's narrative. In his efforts to protect his daughter Beatrice, Dr. Rappacini seeks to protect her by wrapping her in poison to which she has developed an immunity because of her father's potions.  But, in the end she is susceptible to the envious service of Rappacini's rival, Dr. Baglioni, who convinces the innocent Giovanni to give her an antidote which destroys her.  Thus, Giovanni becomes corrupted morally as his selfish desires for Beatrice effect her demise. For, the fatal love of science of Rappacini and Baglioni produces moral conflicts with characters that ultimately result in estrangement and death.  Beatrice tells Giovanni,

"There was an awful doom...the effect of my father's fatal love of science--which estranged me from all society of my kind."

In his effort to protect his daughter, Rapaccini has severed Beatrice from all other human contact than himself. And, in loving her Giovanni has separated himself from the rest of the world.

What is the moral lesson in the story "Rappaccini's Daughter" from a Romanticism perspective?

Because of her father's evil experiment, his lovely daughter Beatrice poisons all that she breathes on and touches. This means she has to stay inside her father's garden, otherwise she might harm or kill other humans.

Giovanni sees her from afar and falls in love with her. He makes his way into the garden and learns her secret. However, he too begins to turn into a being who poisons all around him.

Giovanni becomes angry, thinking Beatrice lured him into the garden to make him like herself. Now, he fears he is trapped with her: he accuses her of orchestrating this to have a companion. He will not believe her protests and speaks to her with bitter accusation.

When he comes to her with an antidote, she drinks it and dies—as with everything else in her life, her body reacts in the wrong way, so the antidote is poison to her.

The moral of the story, as with other Hawthorne stories, is that true love accepts a person the way they are. What Giovanni objected to was only a superficial bodily problem. He should have been able to see through her poisonous body to her pure soul—but he could not. As the narrator says, Giovanni only had the "cunning semblance" of love, not the depth of real love.

If Giovanni's love for Beatrice had not been shallow, he would have accepted her the way he found her, trusted her words, joined her in the garden, and not tried to fix her. Her soul would have mattered more to him than any physical issues. Instead, his lack of true love and poisonous accusations lead to her death. As Beatrice says to him, isn't there

more poison in thy nature than in mine?