I have nothing against romance, which in murim/cultivation manhwa I think actually matters that the MC always has one experience which deeply will affect his word view.
Yet in this context, the FL is his former fiancé with whom the engagement was broken.
She wasn't wrong as the OGMC body was truly trash in attitude if I remember well, so it was deserved.
But, I still think it is embarrassing now that their engagement was broken at first, they should have moved on and maintained a platonic relationship.
Belenka was the enemy, because of her Lucy's people died! I'm lost.