Seraphina was a very "instinctive" person, and because of this, her beastliness was so pure. She didn't have any grand ideals in her heart, and the logic of her actions was basic enough, simple enough — protect what she likes, destroy what she dislikes, devour the stronger, that's all.
So, Ansel's taming plan also followed Seraphina's instincts, what she loved, what she cared about, what she disliked, what she hated, what she needed...replacing those things with Ansel himself and the corresponding tragic fate, everything was solved.
Moreover, Seraphina, who followed her instincts, was more easily influenced by her body. The desires and restlessness in her body would drive her to get closer to Ansel, but...Ravenna was different, or rather, completely opposite to Seraphina.
