Yep, I agree. A schedule, believe it or not like I said, will work best.
You said he wants sex "all the time." Do you mean, all hours of the day or night? Or do you mean he's interested every night? If he's demanding sex several times a day, I'd say he's a sex addict and you can't change that, so you should consider moving on. If you just mean he wants to have sex every night, offer hand jobs sometimes, blow jobs if you feel like it, and sex other nights, and build in some days where you get a break. Offer him this kind of schedule sometime in the day (i.e., not when you're not turning in for the night), and see if he would accept this as a compromise. If he won't, then you do have some thinking to do about how long this relationship is going to last.
The classic argument!! Tell him how you feel and find a happy medium is my advice. Before my ex-wife and I split, I was kind of the same way. It was either the complete act of sex or nothing. She wasn't the kind that would just give me oral sex to completion and I would be happy. So, we came to an agreement that I wouldn't bother her any time during the week but Friday and Saturday it was on - in fact, a further compromise included that out of the four weekends, all were "making love" but one weekend was mine. Both included lots of foreplay; however, hers included hot baths, candles, music, giving her massages, and getting an erection just from kissing. It was missionary style sex with lots of kissing and touching. If she felt like giving oral, that was fine but I didn't expect it. Plus, there were other ways to give me an erection anyway. Less I digress.
But, the one weekend that was mine was sex. Down and dirty, big sloppy oral, talking dirty, costumes, fantasies, you name it. It actually worked out for a good long while (her hysterectomy changed everything). So, maybe work it out???
If he doesn't budge and its a big factor for you, sex, like finances, is usually enough to break a relationship. It may be difficult but it happens . . . keep us posted!!!
You don't have to screw all the time. Just give him oral or a hand job and explain that your body needs time to recover from sex. Make sure he know you love him and want to be with him but you physically can not do it all the time. Make sure to talk to him and ask him not to fight with you when you guys talk about this.