5. Let your boyfriend know that he will regret it if he cheats.
You can let your boyfriend know that you will make his life hell if he ever cheats on you. For example, you could agree that you would control his life or that he would have to pay a large fine if he cheated. However, this strategy has disadvantages—planting fear in your boyfriend’s mind will not solve the issue, which is to eliminate his temptation to cheat.