[TOMT] [movie] [2000s/2010s] "she's gone man-vegan" romcom

I have had this quote from a movie rolling around in my head for days, and I cannot place it to save my life. A female protagonist says she has gone man-vegan—"you only miss them for the first two weeks!"

Then, naturally, she meets a man and gives up her vegan ways.

I want to say one of the characters in the conversation had a British accent but I could be wrong.

Thanks for any help!