Hi Welcome to HCM.
Certain drugs are known to reduce the libido. such as those used for high blood pressure
Most of the time it is controlled by our mental state. Indulge in lot of foreplay before actually engaging in intercourse, find out what kind of fanatsy stimulates him most and try to re-enact thos fantasies if possible, wear revealing sexy dresses.
If none of these works consult an urologist
who will need to evaluate his health and then prescribe drugs for erectile dysfunction
Wish you both all the best.