If I had married the guy I was dating when I was 19 (he was 22 then), I'd probably be sounding a bit like this girl right now, especially after turning 21. I'm turning 27 this summer and I've changed *so much* since I was 19, of course... and most of that change happened when I was between 20 and 24 years old. I had a fairly sheltered life up until I turned 21, and after that I started exploring things and really having fun. So I don't know if this is her case, but it may be part of it.
When it comes down to it, though, I have no idea what she's thinking and feeling, because I'm not her, and I'm not married to her. That's why this comes down to you and her, not you and the TFP. You must learn the TFP mantra: COMMUNICATE.
I don't mean just sit around and talk on the couch after watching TV; I mean, set up a specific time when both of you know what's going to be talked about (your relationship), and dig in REAL deep with each other. Read her what you wrote on the TFP, if it's necessary. Start all your statements with, "I feel _____ when you _____."
And be prepared for some shit to hit the fan. But that's what being in a committed relationship is all about; exposing all your shit and being ready to take all of the other person's shit, and moving forward together (I mean yeah, there's also the part about enjoying time together, etc... but right now you need to air out the shit). There's no other way to maintain (or obtain, if you don't have it) intimacy.