@LoveU123,
The only reason I could think of to pretend to cheat without actually cheating is to prove a point. There are two possible reasons I can think of
1. He thinks you are jealous and controlling. He wants to prove you wrong so you won't keep suspecting him.
2. He thinks you are taking him for granted. He wants you to know that he doesn't need you.
In either case, this is horrible communication. These kind of games are never good in a relationship. If you both want the relationship to work, you should sit down together and talk directly about what is going on.