Responses
Perhaps its
"No, I only charmed the princess!"
Tho i cant be certain bc i havents read it but that characters all fit your description based on the summary and cover photo.
https://www.mangago.me/read-manga/no_i_only_charmed_the_princess/
There's one that's super similar to this that I lost; that this one's cover reminded me of.
The FL has white hair, and she makes a deal with the royal family to marry into it. The Emperor, Crown Prince, and a younger Prince all have black hair, and their little sister has pink hair (I think). Though they do not trust her because of the shit family she comes from; the CP agrees to marry her. And she cuts ties with her family. She's more invested in the young princess than the others. (The whole family is SUPER protective over the Princess, and they tried to keep the two apart) I think her goal was not only to get away from her family but to help the Princess. I remember the FL and Princess got along really well. In it- The FL took a trip to a cave with the CP to get a sword (?) And the guardian liked the FL enough to leave the cave with her. If I'm remembering right the guardian looked like a giant white wolf.
Does anyone know the title to this one?