I was in your shoes OP.
Before I had kids (and lost my sex drive) I felt the same about my DH. I never got to the bottom of it (in our conversations), but I think he had confidence issues. He said all of the right things about loving me and wanting sex, but he hardly ever felt like he wanted it and when it did happen, he would often lose interest half way through.
I found it REALLY hard and soul destroying. I never thought I'd feel that way, but it was so hard not to take it personally. Even if my rational head told me it wasn't anything to do with how he felt about me, I couldn't help feeling that way. I felt rejected over and over again. Its so difficult to have a conversation about it as any comments that sound like they could be criticisms or negative just make the problem worse. Having to be positive about it and hide how awful I really felt (FOR YEARS), was really difficult. Even though I wanted to have sex, I started to dread it. I felt like I was waiting for the rejection. The issue completey disappeared after we had children because I now have no sex drive! It's taken the pressure of him.
I know our situaitons are not exactly the same, but sex is an important part of a relationship and affects how you feel about that relationship and your self-esteem. There is nothing wrong with wanting to have more sex in a relationship.
The bit that is worrying are some of the phrases and language you've used, that other posters have commented on. I hope you do not use those phrases to your wife and that it is just 'lad speak' and not a true reflection of how you feel. She needs to feel loved, not that you don't care how you are making her feel in your conquest for sex (which is not loving). Please take heed of the comments people have said about the language you are using and think about how you can express it nicely.
You sound like you are laying the groundwork for justifying why you are going to leave her or have an affair. This is because your language is EMOTIONALLY DETATCHED. Especialy when you talk about 'how long should I give it - 2 years, 5 years?'. I hope that is not the case. You have a child together and need to work at the relationship.
There is no easy answer to this issue you are experiencing. It's hard but you have to be positive, loving, talk to her nicely about how she feels in the relationship, be understanding about how she does not feel like having sex at the moment, give it time, have child-free time together, try to do things you used to do before children, flirt, laugh, talk. Perhaps you could see a counsellor just to discuss how you feel and how you can change your mindset a little and think more positively (there is nothing wrong with you, it's not a criticism, but it might help).