Ask your man how much he masturbates and I think you will be very surprised. If he says anything less than once per day he is probably lying. Men should only cum once every 5-7 days (depending on age) and testosterone levels. Here is a very general guideline to help you find his correct level:
20-29 Years – Three to five days
30-49 Years – Five to seven days
50-59 Years – Ten to twelve days
60+ Years – Twice a month tops.
He should always ask your permission before masturbating, few men have enough self control to limit their masturbation on their own. If you suspect that he is masturbating behind your back, have him cum on your chest and examine the amount of cum. You know the regular amount of cum that your man can produce. If his levels are too low, you know he is not being truthful about his masturbation habits.
This is very common and almost all men require a chastity device to get their habits under control. There are simply too many distractions and porn and erotic images are too easily accessible. If he has an accident and breaches your trust, you should punish him by whatever means you use in your relationship but that punishment should be much less severe if he tells you about it rather than you catch him lying to you about it based on his low semen volume.
Sexual urges can be very distracting and your man will grow to appreciate your help with controlling his urges. His testicles spend every waking hour producing sperm and hormones which his body tells him that he needs to release frequently. You want to step in and stop that release to ensure that you get the best man that he can possibly be. Frequent masturbating changes his mindset from wanting to please one woman to lusting after multiple women. Control that mindset and ensure that every release of his semen are with you. If you have him on a ejaculation cycle, obviously this would be different.
If you must allow him to masturbate without you (long distance relationships, frequent travel etc) have him masturbate to a photo of you or a pair of your panties. Have questions? Comment below.