SOLVED. YA romance and fantasy about a girl who kills another in order to impersonate her as a prince's fiancée. Spoilers ahead.

[Maggie]

There's a girl (A) sent to kill another girl (B). Girl B is a prince's fiancée, and girl A is tasked with taking B's place and impersonating her (don't remember the purpose of this mission). Girl A ambushes girl B on her way to the prince's castle/palace/ place he lives and is accompanied by one to three guys who help her dispose of girl B and her companions.

After girl A kills girl B, she goes to the castle/palace and pretends to be her, and at first it works. At some point there is a portrait discovered of the dead girl B, and girl A is found out to be a fraud. She escapes, though.

All throughout the period of time girl A was pretending, she and the prince developed a real bond.

I think girl A has a sister.

I read the book in 2019, but I'm pretty sure it had already been published for quite a bit. Definitely 2010s, most possibly from 2015 onwards.

[Maggie]

Ruined

I found it! No worries :)