One thing I might suggest is that you don't tell him how to respond to you, just that you would like a response by a certain date. I guess...the way I see that is that he HAS to respond to you twith a letter when that might not be his best communication style...I hope that made sense. Of course he might not have taken it as his only option for response...it's just how I read it.
Also...take some time to define for yourself what you believe him "wanting you" is, what would it look like? What can he do that will communicate he wants/desires you? So you can clearly communicate that to him. If you go back through several of our postings you'll notice that many people get caught up in their spouse "wanting" them or truly desiring them, true...some of the things we believe shows "want/desire" are the same...but some are different and very individual. Also, when he does do these things beware of not trusting that he's doing it because he wants you....but because you told him he needs to do that, so he's doing it to please you. Regardless of why he does what he does to show "want"...whether it's because you asked him to do it or it's coming from a place deep within him...he's doing it because he loves you and because he wants to make you happy.
I warn you of this because many people have voiced what their spouse could do to show want...and then when their spouse does these things they think they're doing it because they told their spouse that's what they needed...so they think they have to; it begins to become not good enough and that ends up putting your spouse in a no-win situation. Don't fall into that trap.