This week's tweet of literal interpretation:
If someone were to talk to me the way Christian Grey talks to Ana, I'll literally melt.— S (@stefiiiiii_) October 28, 2014
So, yes, this was (apparently) said by Christian Grey to Anastasia in 50 Shades of Grey. Having read the tweet, I simply searched for a quote which I believed could actually make someone melt. This seemed a good candidate.
If you don't get the last panel, click here.
Also, why not download a PDF of the entire comic!