Unfortunately, if sexual interest has declined over a period of time then it takes as lot of effort and time to get things back in gear. It is easy to forget the rituals of courtship. One or both members of pair can start with little presents from time to time and remembering what the partner likes for entertainment and enjoyment. Find the right foods to prepare or the right restaurant to make a reservation. All of these little things help to create a climate for intimacy.
Many couples report that living out fantasies is very sexually exciting.
For example, a man goes to a bar and soon a woman comes in. Both people can really enjoy this. It takes a little work to recall sexual fantasies Or invent new ones that are sexually stimulating and then figure out how to put them in action. Unfortunately, if a relationship has deteriorated to the point where there is very little affection or caring between the partners, there is need for some more general discussion. If nothing of value comes out of such a discussion both people have to question why they stay in the relationship.