I am designing an alien species of organism (not necessarily intelligent, in fact, probably not). My current settings are these:
The female is very large (bigger than cattle, smaller than elephants), have strong, pointed mouthparts for skewering prey or enemies and are capable of sudden bursts of speed. The males can fly, and are around the size of vultures or other large birds. They also have somewhat dexterous claws for gathering edible vegetables or processing meat.
The dynamic of the sexes is so: one adult female is followed by numerous males (perhaps 5 or 8). The males try to do the female favours, such as scouting for prey or gathering food for the female (both sexes are omnivorous, but prefer meat when it is available). As a reward, the female will become more intimate with a contributing male, and when sufficiently intimate, will mate with it.
I want to know if this system will be evolutionarily stable, as in whether or not some new system will take its place spontaneously as time goes on. For example, will more docile and sex-prone females become more successful than their more demanding counterparts, and hence push the latter out of the gene pool? Or perhaps some kind of sexual selection, similar to those that caused the appearance of peacock tails and the like, cause more "charismatic" male to be selected over diligently contributing males and hence destroy the system?
(I am also leaving out some details like what method of reproduction the organism uses (i.e. egg-laying versus live-birth) in case these variables can be set to stablize/disrupt the system)