You'd get significant sexual dimorphism.
Firstly, there's no reason for the males to be intelligent, there's no apparent advantage to it. It's a lot of energy to burn for such a short lifespan.
Since one sex is intelligent and the other not, you'd need a system by which the females picked partners. Are they strong? They can't risk fighting as males are not disposable. Are they colourful or showy? Devious? A mix of all the above?
Sex balance among the spawn: You'd need significantly more males than females. At least one male for every litter that a female would bear in her lifetime, per female offspring, per litter. They'd have to breed like rodents. You'd probably need to have a flat minimum of one female and four males per litter to increase population at all. This still only allows a maximum of 4 litters per female, which is ridiculously low in the real world.
The males mating to death? Not such a problem. Though in these cases they mate with as many females as they can before they crash and burn.