Real connection?? Not once in his letter did I hear him say, "I miss loving my wife, I miss feeling connected to my wife"...not once did I hear him wonder if HE was giving her what she needed to feel connected. Sex isn't the issue...but he's made it his personal issue.
Men and women are fundamentally different (I'm hoping he already knows this, or he REALLY has a lot to learn.) Most women when they are in love with someone, require a connection, a romantic bond that excites them and drives them closer. It usually takes an emotional jump before a physical one. If she isn't interested in his physical jumps, perhaps he should pay more attention to her emotional ones and see if HE is really giving her what she needs either.
He should find out what is missing for HER, and try to help her fulfill those needs. He might be surprised to find that once she knows her needs are recognized and important to him, she will reciprocate.
You may also want to check the answers to:
"How do I get my wife to make whoopie?"
A guy who is in the same situation:
"Why do I refuse intimacy with my sexy girlfriend?"
A woman who is no longer attracted to her boyfriend:
"Do I settle for a relationship without sex?"