Thanks for the suggestions so far.
My other suggestion would be to figure out her love language. There's a book, The 5 Love Languages, but also a website. Just google it and you can take a quiz. This helped me and my H quite a bit with the intimacy thing.
How is the general affection between the two of you? Nonsexual touches? Conversation? Cuddling?
I googled the test and I could tell without a doubt of wife's love language is receiving gifts. She's an ambitiously possessive girl and loves gifts more than anything else. It's something I get better with as our relationship progress.
As for general affection, we show it daily to each other. We hold hands, hug, kiss (no more than a peck), cuddle when we watch TV and before bed, give each other back rubs... It rarely leads to anything though. Hell, even when we cuddle, I hint towards sex by sensually touching her in subtle, sensitive areas. She doesn't get the hint. I confronted her about this and she said I'm missing steps between sensual touching and sex. I asked her what they were and she shrugged. /facepalm.
But from an even less detailed level, sex is so different for all the people in the world. Even if you speak the right language, so to speak, other things are still necessary. She has to be interested in sex (which it sounds like she's not). She has to be physically attracted to you. You mention that you've gone through the Nice Guy posts. Another site that may help you is marriedmansexlife.com. (Disclaimer: I haven't used the information on there to my own benefit like I have the 5LLs; however, the information there gets considerable positive feedback.)
I've frequented marriedmansexlife.com, especially the alpha/beta sections. Being more alpha has boosted my self-esteem but left little to no impression on my wife. She likes how I'm more responsible, confident, and commanding but it doesn't produce the desired results. I lay on more of the alpha but it makes her see me as an overconfident jerk. One complaint she always had was how underweight I was. I was underweight and in the past 2 months, I've been working out constantly and I've gained 20 pounds of mostly muscle. She's happy that I've done this but it's done nothing to increase her physical attraction in me. I shopped for new clothes too that she says I look good in, but still I don't see and increase in attraction.
What is it that you do that meets her needs, and makes her value you and the marriage?
Once you identify it ... stop doing it.
That will get her attention and cast the issue in an entirely different light.
Makes sense. I'm being deprived while trying to please her. I don't want to be a jerk and come off like I don't love her but I'd rather do this than continue to hear her tell me that she loves me but doesn't want to fulfill my needs. I'll have to work on this.
A question I have is when I was discussing this with my wife, she felt that I think I should get sex because we're married. I do feel this way but I feel that since we both love each other, we pursue to fulfill each others needs in the relationship. Since sex is a need for me, and I've made this clear to her, I feel that she should be pursuing to fulfill that need out of love for me. Am I out of line to think this way?