I don't really understand dating or relationships in general but I'll have a go at the question. Consider the process of reproduction itself. Countless male sperm cells come together to fuse with the one female egg cell to synthesize the zygote, not the other way around. This very simple fact of biology make females more 'precious' or scarce as far as mating is concerned. Also, by observing people's behaviors in everyday life, it is apparent that men seem much more eager to find a suitable female. This is consistent with our original analysis of the issue. Simply by the way men are 'built', they are able to/ and should be the ones putting in the effort.

Unfortunately this area of discussion isn't in my familiar territory but I thought I ought to add to the ongoing debate. Hope it helps.