Women usually need intimacy for hours and hours in order to feel inclined toward sex, but they also need help with whatever is tiring them out so that they have energy left for sex.
Despite all the information you hear in our culture, sex is physically exhausting for many women, even if they just lay there and appear to be doing nothing - they are bearing the weight of your body (regardless of the position you choose), and a huge emotional weight as you move past all of their physical/emotional barriers and right into their very bodies! Perhaps it is difficult for a man to imagine, but at least understand that sex is much more of a big deal to most women than to most men.
Many women get "in the mood" over the strangest things (to men). Many say that one of the sexiest things their husbands can do is to encourage them to have a relaxing bubble bath while he does the dishes and cleans the house. Most women need to feel relaxed in order to enjoy sex. Also, they need to know that the sex itself will be enjoyable for them, too. That means, it needs to involve an orgasm for her, and NOTHING that he wants that is uncomfortable for her! You need to never, never ask her to do anything that she seems reluctant to do, sexually, or you are turning the whole experience into something for her to dread.
I disagree with Dr. Laura. One of the very WORST things you can do to your sex life is for either of you to have sex when you don't want to. It damages trust, and turns your sexual life into something other than intimacy and love-making. It makes it about getting off, rather than connecting, and you don't want your wife to EVER feel that she is just a thing to be used for your physical gratification! No, no, no! That may be the kiss of death to your happy sex life!
See Dr. Harley's site:
Meeting the Need for Sexual Fulfillment:
http://www.marriagebuilders.com/graphic/mbi5013_qa.htmlChanging a Willingness to Make Love into a Desire to Make Love:
http://www.marriagebuilders.com/graphic/ss/50-1.htmlHopefully that will get you started. Remember, she is very, very different than you are - physically, emotionally, and even spiritually. If her needs are met, she will want you sexually. Remember that - If her needs are met, she will want you sexually.
Do what you can to learn what she needs, or even to help her to figure out what she need, if she isn't sure.
Check here for the Emotional Needs questionnaire:
http://www.marriagebuilders.com/graphic/mbi4501_enq.htmlAnd here for the Love Busters questionnaire:
http://www.marriagebuilders.com/graphic/mbi4502_lbq.htmlBest of luck. Whatever you do, don't try to get her to have sex with you until she is ready and willing, at least, and preferably not until she really wants to!