Real-world evidence is that young, childless, never-married women are the most attractive marital prospects, by far.
Men aren't lining up to wife up divorced moms, although they're probably more attractive than never-married moms.
Discussion
You are comparing smart and high-value men with average and normal men; and the highest value woman with the average woman. The truth is, if a woman isn't batshit crazy, infertile and obese, most men are blind to the implications of being a stepfather and would gladly marry a single mother.