I can only talk for myself, but I personally don't mind who a woman has been with before. I understand your point though, women are often called sluts where men would be called alpha. Most societies are quite patriarchal in nature, Western civilization not in the slightest. In my opinion this is certainly true the more Southern you go in Europe.
In my opinion if too few women would be available you'd see men more going after married women. I think this is also why in Islam women need to stay at home and sexes are segregated.