I'm reading I Became a Millionaire's Daughter right now and I love the relationship between the MCs. Especially how the guy warms up to her and smiles more instead of being cold.

I'd like to read more stories that are similar in that aspect.

Lucia

i think this will be perfect then 🙂

The Lady and Her Butler

this is kinda the opposite since the girl is super cold at first, but you might like it