I had to re-read the story to get back here.
I hate how everyone has treated Aria and Rafilia up to this point. Imagine that you were marrying the love of your life, not knowing what his brother looked like (See Aria's introduction chapter. She most likely knew about Rovel since he was from the same household, but, she didn't know what he looked like), and then "falling in lust" with this new person. Fair. Every human has lustful thoughts. It's to be human.
Then, on your wedding day, the Goddesses of Truth and Marriage slap you on the wrist and lightly brand you for daring to have lustful thoughts somewhere in your subconsciousness. Then, the QUEEN OF SPIRITS herself shows up to say some vague nonsense about a "sin" and imply that you are two-timing on your husband, which you haven't and don't plan on doing. Even the person you've gotten a crush on shows up to shout in your face about being a two-timing cheater without taking the time to listen to you. While she does help you out because she being oh-so-magnanimous she still implies that you are the reason the Royal Family has taken an interest in her daughter.
Then, while you are slowly coming to terms with yourself and "repenting", you get slapped in the face AGAIN as the Hero and Spirit Queen's DAUGHTER shows up to admonish you as well, saying the Royal Family will most likely kill you for potentially weakening the kingdom's military power by having a brand of infidelity. You now have an existential crisis on your hands. You need your spouse to be there for you, but, they are nowhere to be found.
It's now 3 1/2 years later, and you're still wallowing in your fear, anxiety, and depression. You develop a superiority complex and are heavily drinking as a way of mitigating the fear you feel constantly as a literal CHILD's words are haunting you because you had the very human reaction of getting slightly turned on with your spouse's hot sibling, and to make matters worse, your spouse has all but abandoned you.
This doesn't even begin to get into the horrible treatment that your new household's staff have treated your daughter just because she isn't the daughter of the Spirit Queen and Hero.
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Sauvel is a horrible spouse and deserves to be single for the rest of his life. How can he plan to so easily throw Aria and Rafilia away like that? Ellen was right. In any normal circumstance, Aria's "lustful thoughts" wouldn't have mad Vin and Vohl bat an eye. They were needlessly harsh to Aria.