searching for book name

[Kelli]

I am looking for a book where there is a part the girl has to secretly save her man's sister. she goes to bank to withdrawal money and he thinks she is leaving him but she is saving his sister. what is the name?? wanted a friend to read it and can't remember.

[Kelli]

found it thanks

[Juels]

What was it?

[Lobstergirl, au gratin]

https://www.goodreads.com/topic/show/...

[Carla]

Definitely a scene straight from one of the 50 Shades of Grey books.