We've been all through this previously, I think, but I'll add this. It's not very safe to assume much from those texts, IMO, or to assume how another person might text their friends or spouse (unless you ARE their friend or spouse).
We have a great example of this from when (presumably) LV responded to TR's friend or Colby (I don't remember which) pretending to be TR, after she was (as we know now) already dead. She used text-speak, which apparently TR never did. She expressed herself in complete sentences and words. We wouldn't know that unless someone had told us (which they have as reported through MSM). We didn't know what TR's "norm" was.
Likewise, I think it's hard to read much into that CD/TD conversation, other than the apocryphal raccoon tale, which was clearly a ruse. We have no idea what their normal pattern is, and so we can only project what we think is normal. Not everybody uses sarcasm with their spouse. Not everybody responds right away, nor do they necessarily obsessively answer each line of text with an individual response. Not every spouse returns every "I love you" with an automatic "I love you too". Etc. For these reasons, I don't take any special meaning or significance from that text exchange, other than that CD is about as bad a liar as he is a writer.
JMOO