A decade plus ago, Erick Janssen and John Bancroft, both of the Kinsey Institute, proposed “The Dual Control Mode” of sexual response. The idea is sexual response is a result of the “interaction between sexual excitatory and sexual inhibitory processes.” In other words, some things that push us towards sex and other things push us away from sex, and how we feel about sex at any given time depends on which force is currently greater.
Think of it as a math equation, with the things pushing us towards sex being positive, and the things keeping us from sex being negative. If the sum is more than zero, sex is desired, possible, and enjoyed. The greater the sum, the stronger the interest/desire. If the sum is zero or less, sex is not desired, may be difficult or impossible, and will likely not be enjoyed even if it occurs. The greater the negative sum, the more strongly the person is opposed to sex.
In our society men have many things pushing them to have sex, and relatively few holding them back. Women on the other hand usually have fewer things pushing them for sex, and more holding them back.
If your wife is less interested in sex than you are, you can change things by working to increase things that will push her towards sex and decrease things inhibiting her desire for sex, or both. If she is usually around zero it won’t take much to have her often at a positive. If she normally runs -18, it will take far more changes for her to sometimes have a positive sum. This is why major changes sometimes seem to have no effect – they’re not enough to tip the balance. This is also why some women have a “sudden sexual awakening” – enough things changed to tip the balance to the positive side.
You might share this with your wife and ask her if she can identify sexual positives and negatives in her life. Some will be things you can’t effect, but some should be in your power to change. Remove or reduce enough negatives, while adding or increasing enough positives, and you may experience a nice change!