One day when least expected, when your mate comes dragging in the door tired after a long, hard day at work, present this along with a gentle kiss. Just because the flame has become a mild flicker, that does not mean you have lost the love for each other, it just means you need to add a little fuel to the fire. You get the idea.
If you try this and then drill them, to see what they did, whom they were with, and where they went, then the exercise has failed.
This has taken you out of the situation of lying and reconfirmed your honest nature to your mate. At first, this will take some discipline but as you see positive results in the relationship, be encouraged that it is working. There is absolutely no reason why couples at any age cannot get into tickling matches or wrestle on the floor.
A Walk in the Park Spending quality time together where you can talk and just enjoy each others company is critical to a good relationship.