No he doesn't.
Soleil like weak women because that stimule he's male protector instinct. That why he always like the litle sis.
But, whit he's position as marquis, he can't afford a weak women so he choose Illia.
In his point of vue, he only think that Illya is suited to be marquise and they can be partner even if they don't love each other. He doesn't realise he's fault with the litle sis and in some timelines his feeling.
The 3 character in the story are quite isolated for differents reasons.
- Illya : She is victim of timeloop, she can't talk about it and that quite a streesfull situation.
She isn't loved and ingnored by her circle.
She shy and can't express herself.
- Soleil : He is marquis heir, the most powerfull title after royalty, no duke in this country.
People need to have a certain statut to talk to him.
People who have the statut to talk must monitor themself to not ofend him, he have power, he can ruin their family.
conclusion, nobody told him when he cross the line.
- Litle sis : she is sick and confine at home. She can die at anytime so no one burden her with something call "education" or "etiquette". She didn't realise when she cross the line and if that arrive, everyone will pardon her because she grown up like that.
She have a yolo mindset and want to know love before die and the only male at disposition is her futur brother in law.
In conclusion, this situation exist because all the character are isolated for some reason, personnality, position and sickess.