Why do you think massage parlours, prostitution, escort agencies and infidelity are flourishing? Because one of the "partners", usually the male, but not always has got bored with sex. Very simple really.
What is the answer? if this asexual life is not a big deal, then there is no problem, but if sex is important to the male/female then the status quo cannot be allowed to continue.
What can be done to alleviate the situation?
Discussing the problem is the adult way forward, the sensible way forward but unfortunately the results are disappointing and one just gives up.
Marriage counselling........my gut feeling based on the encyclopedia of life is that success rates are equally low.......SO
Prostitution, escort agencies, massage parlours, mistresses and maybe masturbation..........all flourishing. The French and Greeks in particular have already accepted this solution has have many other countries.......but not the Brits.
So.....try and talk it over.......but "you can lead a horse to water, but you can't make it drink.