For me masturbation isn't nearly the same. Masturbation is the 3 day old left overs, and sex is the steak and lobsters.

I think he may border on porn addiction, especially if he sneaks of to watch porn and masturbate instead of having sex. Maybe if you could resist the urge to watch porn for a while it will give his head a chance to reset. Our brains are the largest sex organs.

I've been in a relationship for 8 years and sex drives for me and my wife go up and down. Stress and relationship issues don't improve it either. Me and my wife used to have sex everyday when we first met. After a certain point you have sex with someone so many times, and do so much stuff you run out of things to make it new and interesting. It is difficult to keep the excitement going. We have sex 2 or 3 times a week and that works for us.

Maybe instead of sex everyday he could please you with other stuff. Oral sex, fingering etc. They also sell kits that you can clone his penis if that sounds interesting. I think finding some middle ground may be helpful. Sexual frustration can bleed over to the rest of the relationship and cause problems. I hope you find answers to your problem.