Yes, you should tell him -- to go work for Applebee's. HAHAHAHAHAHAHAHA!!
Thanks, I'm here all week.
Seriously, though, it depends on your guy. Is he a delicate flower who carries his fragile ego around in a padded, shock-proof box with a little sachet inside? Does he get sand all up in his lady bits if you so much as hint at a criticism of him? If so, then YES, by all means tell him, because he's a pantywaist who needs to harden the F up. Or you can just keep coddling him, which must be all kinds of fun.
If he's not a wuss and can handle the truth, sure, you can tell him, but there are ways to do it. You could blurt out over dinner, "What the christ, is this roadkill?", but why insult the guy? At least he's trying, right?
Be cool. Be subtle. Tell him you'd like to do the cooking for a while -- a few days or a month or forever. Buy him some cooking lessons for his birthday. Keep a bowl of Tums on the dinner table or pour yourself a tall cool glass of Imodium for dessert. He'll get the hint.
When I first got married, I did all the cooking because my wife worked full-time while I was in grad school. I made everything -- chicken, fish, pork, rice, potatoes, lentils, tubers, greens, you name it -- and every last bit of it sucked. I mean SUCKED. Bad. I'm talking meals that were completely inedible.
But my wife never had to tell me. I already knew. I tasted my own food; I knew it was vile. But she liked that I was trying, so I kept at it. And whaddya know, before long I got pretty good. Now I cook meals that we can actually eat instead of putting them on the front stoop to scare off stray animals and religious freaks.
So maybe you don't need to tell him at all. Maybe he just needs a little time. He'll either get better at it or get tired of eating his own dreck and quit.
Good luck and happy hurling.
This had better not turn out to be my wife posting anonymously from the next room. Look, I KNOW I overspice; I'm working on it!