I don't necessarily think your DH is playing some kind of power game. It sounds more to me like he just wants to avoid the pressure, and consequent possible disappointment, of TTC each month. I know that every r'ship is different and obviously I don't know you or your DH, but I can see how men might feel pressured when "DTD" becomes "TTC", YKWIM? Not that it takes away the pleasure or fun of it, just that it has a little extra weight (and wait!) to it. He probably also knows that there'll be a tense few days waiting to see if AF arrives and doesn't want you to be disappointed.
I never thought of it that way Sarah. My DP was also very annoyed with me pressuring him to DTD in April last year, became a chore at times, luckily we fell straight away! Men are strange that way aren't they? I think my DP said something like "I'm not a science experiment!" FUNNY

Next year, I am going with the flow me thinks...