Regency romance- lady gets seduction lessons from courtesan

I'm looking for a book i read a few years ago its about a young lady who ahs a crush on an older siblings friend but he just see's her as a young girl with a silly crush so he goes to the continent in hope of decreasing her crush but while he is gone she gets lessons from a courtesan and then seduces him when he gets back, thats all i remember. Please does anyone know what book i am refering to?

it kinda sounds like A Courtesan's Guide to Getting your Man by Susan Donovan and Celeste Bradley