I understand you not wanting to be "too obvious" about your withdrawal, but if your objective is to let her know something is up, you're going to need to make your message clear. What you're talking about is guerilla warfare... or really, bioterrorism, as in, "Gee, I (your wife) am starting to feel bad about the R, is it me or is my H putting nerve gas in the heating system?"
How about a cheerful speech along the lines of, "You know, I'd like to try an experiment. I think we would make better and happier roommates than lovers, kwim? So for the next two weeks, I'm going to practice relating to you like a roommate and see how I feel about that?" (Okay, that's pretty far-fetched )
As for motivation to see a C, you don't need motivation, you just need to pick up the phone and call a few people. There have been some good suggestions on the board )from GEL, I think ) about how to interview a C over the phone to do a first-level compatibility study... don't have time to search right now.
